module misc; % Miscellaneous algebraic code.
create!-package('(misc limits pf sum),'(contrib misc));
endmodule;
module limits;
%% A fast limit package for REDUCE for functions which are continuous
%% except for computable poles and singularities.
%% Author: Stanley L. Kameny.
%% Revised 23 Mar 1993. Version 1.4.
%% Added capability for using either the Taylor series package or the
%% Truncated Power Series Package.
%% Added provisions for transformation of certain irrational functions
%% into rational functions before limit calculation in order to be able
%% to compute series.
%% Changed the algebraic interface so that if limit package fails, an
%% equivalent of the original expression is returned.
%% Allowed for limited recursion through limsimp.
%% Corrected several bugs.
%% Date: 10 Oct 1990. Original version.
%% The Truncated Power Series package is used for non-critical points.
%% L'Hopital's rule is used in critical cases, with preprocessing of
%% <infinity - infinity> forms and reformatting of product forms in
%% order to be able to apply l'Hopital's rule. A limited amount of
%% bounded arithmetic is also employed where applicable.
%% This limits package makes use of the ideas embodied in the
%% limit.red package, by Ian Cohen and John Fitch, 11 July 1990
%% that is in reduce-netlib; in fact, some code is lifted bodily.
%% The idea of using the Truncated Power Series package to compute
%% limits at non-critical points, and the substitutions used in limit!+
%% and limit!- come from there.
load!-package 'tps; %load!-package 'taylor;
lisp(ps!:order!-limit := 100);
switch usetaylor; off usetaylor;
switch crlimtest; off crlimtest;
algebraic
let {sinh(i*~x) => i*sin(x), cosh(i*~x) => cos(x),
sinh(i*~x/~y) => i*sin(x/y), cosh(i*~x/~y) => cos(x/y),
sinh(i/~x) => i*sin(1/x), cosh(i/~x) => cos(1/x)};
algebraic let {tan ~x => sin x/cos x, cot ~x => cos x/sin x};
fluid '(lhop!# lplus!# !*protfg !*msg !*rounded !*complex !#nnn
lim00!#);
global '(erfg!* exptconv!#);
global '(abslims!#);
symbolic(abslims!# := {0,1,-1,'infinity,'(minus infinity)});
% others may be added.
fluid '(lsimpdpth); global '(ld0!#); symbolic(ld0!# := 3);
flag('(limit limit!+ limit!- limit2),'full);
symbolic
for each c in '(limit limit!+ limit!- limit2) do
<<remflag({c},'opfn); put(c,'simpfn,'simplimit)>>;
symbolic procedure limit2(top,bot,xxx,a);
lhopital(top,bot,xxx,a) where lhop!#=0;
symbolic procedure limit!+(ex,x,a);
<<ex := simp!* limlogsort ex;
if a = 'infinity then rederr "Cannot approach infinity from above"
else if a = '(minus infinity) then
limit(prepsq subsq(ex,list(x .
list('quotient,-1,list('expt,'!*eps!*,2)))),'!*eps!*,0)
else limit(prepsq subsq(ex,list(x .
list('plus,a,list('expt,'!*eps!*,2)))),'!*eps!*,0)>>;
symbolic procedure limit!-(ex,x,a);
<<ex := simp!* limlogsort ex;
if a = 'infinity then
limit(prepsq subsq(ex,list(x .
list('quotient,1,list('expt,'!*eps!*,2)))),'!*eps!*,0)
else if a = '(minus infinity) then
rederr "Cannot approach -infinity from below"
else limit(prepsq subsq(ex,list(x .
list('difference,a,list('expt,'!*eps!*,2)))),'!*eps!*,0)>>;
symbolic procedure limit(ex,xxx,a); limit0(limlogsort ex,xxx,a)
where !*combinelogs=nil,lhop!#=0,lplus!#=0,lim00!#=nil,lsimpdpth=0;
symbolic procedure limlogsort x;
<<x := prepsq simp!* x; if countof('log,x)>1 then logsort x else x>>;
symbolic procedure countof(u,v);
if u = v then 1 else if atom v then 0
else countof(u,car v)+countof(u,cdr v);
symbolic procedure simplimit u;
begin scalar fn,args,v; !*protfg := t;
fn := car u; args := cdr u;
v := errorset!*({'apply,mkquote fn,mkquote args},nil);
!*protfg := nil;
return if errorp v or (v := car v) = aeval 'failed
then mksq(u,1)
else simp!* v end;
symbolic procedure limit0(exp,x,a);
<<exp := simp!* exp;
if a = 'infinity then
limit00(subsq(exp,{x . {'quotient,1,{'expt,x,2}}}),x)
else if a = '(minus infinity) then
limit00(subsq(exp,{x . {'quotient,-1,{'expt,x,2}}}),x)
else if a neq 0 then limit00(subsq(exp,{x . {'plus,a,x}}),x)
else limit00(exp,x)>>;
switch lim00rec; on lim00rec;
symbolic procedure limit00(ex,x);
begin scalar p,p1,z,xpwrlcm,lim,ls;
if (lim := crlimitset(p := prepsq ex,x)) then go to ret;
if not lim00!# then
<<lim00!# := not !*lim00rec;
p1 := factrprep prepsq ex;
if (xpwrlcm := xpwrlcmp(p1,x)) neq 1 then
<<ex := subsq(ex,{x . {'expt,x,xpwrlcm}});
p1 := factrprep prepsq ex>>;
if (z := pwrdenp(p1,x)) neq 1 then
ex := simp!*{'expt,p1,z};
if (lim := crlimitset(p := prepsq ex,x)) then go to ret>>;
% tps has failed because ex has a branch point at a or is undefined
% at a or tps itself has failed or Reduce has not recognized the
% numeric value of an expression.
if %xpwrlcm and xpwrlcm>1 or
lsimpdpth>ld0!#
then lim := aeval 'failed else
<<lsimpdpth := lsimpdpth + 1; ls := t;
lim := limsimp(p,x);
if prepsq simp!* lim = 'failed and lsimpdpth=1 then
<<exptconv!# := nil; p := expt2exp(p,x);
if exptconv!# then lim := limsimp(p,x)>> >>;
ret: return
<<if ls then lsimpdpth := lsimpdpth - 1;
if not z or z = 1 or lim=0 then lim
else if (ls := prepsq simp!* lim) = '(minus infinity)
then if (-1)^z = 1 then aeval 'infinity else lim
else if ls member '(infinity failed) then lim
else mk!*sq simp!* {'expt,prepsq simp!* lim,{'quotient,1,z}}>>
end;
symbolic procedure factrprep p;
begin scalar !*factor;
!*factor := t;
return prepsq simp!* p end;
symbolic procedure expt2exp(p,x);
if atom p then p
else if eqcar(p,'expt)
and not freeof(cadr p,x) and not freeof(caddr p,x) then
<<exptconv!# := t; {'expt,'e,{'times,{'log,cadr p},caddr p}}>>
else expt2exp(car p,x) . expt2exp(cdr p,x);
symbolic procedure xpwrlcmp(p,x);
if atom p then 1
else if eqcar(p,'expt) and cadr p = x then getdenom caddr p
else if eqcar(p,'sqrt) then getdenomx(cadr p,x)
else lcm(xpwrlcmp(car p,x),xpwrlcmp(cdr p,x));
symbolic procedure getdenomx(p,x);
if freeof(p,x) then 1
else if eqcar(p,'minus) then getdenomx(cadr p,x)
else if p = x or eqcar(p,'times) and x member cdr p then 2
else xpwrlcmp(p,x);
symbolic procedure getdenom p;
if eqcar(p,'minus) then getdenom cadr p
else if eqcar(p,'quotient) and numberp caddr p then caddr p
else 1;
symbolic procedure pwrdenp(p,x);
if atom p then 1
else if eqcar(p,'expt) and not freeof(cadr p,x)
then getdenom caddr p
else if eqcar(p,'sqrt) and not freeof(cadr p,x) then 2
else if eqcar(p,'minus) then pwrdenp(cadr p,x)
else if car p member '(times quotient) then
(<<for each c in cdr p do m := lcm(m,pwrdenp(c,x)); m>>
where m=1)
else if atom car p then 1
else lcm(pwrdenp(car p,x),pwrdenp(cdr p,x));
symbolic procedure limitset(ex,x,a);
if !*usetaylor then
<<!*protfg := t;
ex := errorset!*({'limit1t,mkquote ex,mkquote x,mkquote a},nil);
!*protfg := nil;
if errorp ex then nil else car ex>>
else % use tps.
begin scalar oldpslim;
!*protfg := t; oldpslim := simppsexplim '(1);
ex := errorset!*({'limit1p,mkquote ex,mkquote x,mkquote a},nil);
!*protfg := nil; simppsexplim list car oldpslim;
return if errorp ex then nil else car ex
end;
symbolic procedure limit1t(ex,x,a);
begin scalar nnn, vvv;
ex := caaaar simptaylor {ex,x,a,2};
if not eqcar(ex,'taylor!*) then return nil
else ex := cadr ex;
% ex is now the list of coefs and values, but we need the lowest
% order non-zero value, which may not be the first of these.
loop:if null cadar ex and cdr ex then <<ex := cdr ex; go to loop>>;
if not numberp (nnn := caaaar ex) then return nil else
!#nnn := nnn;
vvv := cdar ex;
return
if nnn>0 then 0
else if nnn=0 then mk!*sq vvv
else if domainp(nnn := car vvv) and !:minusp nnn
then aeval '(minus infinity)
else 'infinity
end;
symbolic procedure limit1p(ex,x,a);
begin scalar aaa, nnn, vvv;
aaa := mk!*sq simpps1(ex,x,a);
!#nnn := nnn := mk!*sq simppsorder list aaa;
vvv := simppsterm1(aaa,min(nnn,0));
return
if nnn>0 then 0
else if nnn=0 then mk!*sq vvv
else if domainp(nnn := car vvv) and !:minusp nnn
then aeval '(minus infinity)
else 'infinity
end;
symbolic procedure crlimitset(ex,x);
(begin scalar lim1,lim2,n1,fg,limcr,!#nnn;
lim1 := limitset(ex,x,0);
if null lim1 then if r and c then return nil else go to a;
if (n1 := !#nnn) < 0 or lim1 member abslims!#
or r and c then return lim1;
a: if not !*crlimtest then return lim1;
if not r then on rounded; if not c then on complex;
if not (lim2 := limitset(ex,x,0))
or !#nnn > n1 then <<fg := t; go to ret>>;
if !#nnn < n1 or lim2 member abslims!# then go to ret;
% at this point, both lim1 and lim2 have values. If they are
% equivalent, we want lim1; otherwise lim2.
if (limcr := topevalsetsq lim1) and
evalequal(prepsq simp!* lim2,prepsq limcr)
then fg := t;
ret:if not r then off rounded; if not c then off complex;
return if fg then lim1 else lim2 end)
where r=!*rounded,c=!*complex,!*msg=nil;
symbolic procedure topevalsetsq u;
<<!*protfg := t;
if not r then on rounded; if not c then on complex;
u := errorset!*({'simp!*,{'aeval,{'prepsq,{'simp!*,mkquote u}}}},
nil);
!*protfg := nil;
if not r then off rounded;if not c then off complex;
if errorp u then nil else car u>>
where r=!*rounded,c=!*complex,!*msg=nil;
put('times,'limsfn,'ltimesfn);
put('quotient,'limsfn,'lquotfn);
put('plus,'limsfn,'lplusfn);
put('expt,'limsfn,'lexptfn);
symbolic procedure limsimp(ex,x);
% called when limit1 has failed, to apply more sophisticated methods.
% output must be aeval form.
begin scalar y,c,z,m,ex0;
if eqcar(ex,'minus) then <<m := t; ex := cadr ex>>;
ex0 := ex;
if not atom ex then % check for plus, times, or quotient.
<<if(z := get(y := car ex,'limsfn))
then ex := apply(z,list(ex,x))>>
else <<if ex eq x then ex := 0; go to ret>>;
if y eq 'plus then go to ret;
if y eq 'expt then if ex then return ex else ex := ex0 . 1;
if z then<<z := car ex; c := cdr ex>>
else <<z := prepsq !*f2q numr(ex := simp!* ex);
c := prepsq !*f2q denr ex>>;
ex := lhopital(z,c,x,0);
ret: if m and prepsq simp!* ex neq 'failed then
ex := aeval lminus2 ex;
return ex end;
symbolic procedure lminus2 ex;
if numberp ex then -ex
else if eqcar(ex,'minus) then cadr ex
else list('minus,ex);
symbolic procedure ltimesfn(ex,x); specchk(ex,1,x);
symbolic procedure lquotfn(ex,x);
% (if eqcar(n,'expt) and (nlim :=lexptfn(n,x))
specchk(cadr ex,caddr ex,x);
symbolic procedure lexptfn(ex,x);
if not evalequal(cadr ex,0) and limit00(simp!* caddr ex,x)=0
then 1;
symbolic procedure specchk(top,bot,x);
begin scalar tlist,blist,tinfs,binfs,tlogs,blogs,tzros,bzros,
tnrms,bnrms,m;
if eqcar(top,'minus) then <<m := t; top := cadr top>>;
if eqcar(bot,'minus) then <<m := not m; bot := cadr bot>>;
tlist := limsort(timsift(top,x),x);
blist := limsort(timsift(bot,x),x);
tinfs := cdr(tlogs := logcomb(cadr tlist,x)); tlogs := car tlogs;
binfs := cdr(blogs := logcomb(cadr blist,x)); blogs := car blogs;
tzros := car tlist; tnrms := caddr tlist;
bzros := car blist; bnrms := caddr blist;
if tlogs and not blogs then
<<top := triml append(tlogs,tnrms);
bot := triml append(bzros,append(binfs,
append(bnrms,trimq append(tinfs,tzros))))>>
else if blogs and not tlogs then
<<bot := triml append(blogs,bnrms);
top := triml append(tzros,append(tinfs,
append(tnrms,trimq append(binfs,bzros))))>>
else
<<top := triml append(cadr tlist,trimq bzros);
bot := triml append(cadr blist,
append(bnrms,trimq append(tzros,tnrms)))>>;
if m then top := list('minus,top);
return top . bot end;
symbolic procedure trimq l;
if l then list list('quotient,1,
if length l>1 then 'times . l else car l);
symbolic procedure triml l;
if null l then 1 else if length l>1 then 'times . l else car l;
symbolic procedure limsort(ex,x);
begin scalar zros,infs,nrms,q,s;
for each c in ex do
if (q := numr(s := simp!* limit00(simp!* c,x)))
and numberp q and not zerop q then nrms := q . nrms
else if null q or zerop q then zros := c . zros
else if caaar q memq '(failed infinity) then infs := c.infs
else nrms := (prepsq s) . nrms;
return list(zros,infs,nrms) end;
symbolic procedure logcomb(tinf,x);
% separate product list into log terms and others.
begin scalar tlog,c,z;
while tinf do
<<c := car tinf; tinf := cdr tinf;
if eqcar(c,'log)
or eqcar(c,'expt) and eqcar(cadr c,'log)
or eqcar(c,'plus) and
(eqcar(cadr(c := logjoin(c,x)),'log)
or eqcar(cadr c,'minus) and eqcar(cadadr c,'log))
and freeof(cddr c,x)
then tlog := c . tlog else z := c . z>>;
return tlog . reversip z end;
symbolic procedure logjoin(p,x);
% combine log terms in sum list into a single log.
begin scalar ll,z;
for each c in cdr p do
if freeof(c,x) then z := c . z
else if eqcar(c,'log) then ll := (cadr c) . ll
else if eqcar(c,'minus) and eqcar(cadr c,'log) then
ll := list('quotient,1,cadadr c) . ll
else z := c . z;
if ll then ll := list list('log,'times . ll);
return (car p) . append(ll,reversip z) end;
symbolic procedure timsift(ex,x);
if eqcar(ex,'times) then cdr ex
else if eqcar(ex,'plus) then list logjoin(ex,x)
% for plus, combine log terms, change infinity - infinity to
% inner quotient.
else list ex;
symbolic procedure lplusfn(ex,x);
% combine logs and evaluate each limit term. if infinity - infinity
% is found, attempt conversion to quotient form for lhopital.
begin scalar z,infs,nrms,vals,vp,vm,cz,vnix;
lplus!# := lplus!# + 1;
% write "lplus#=",lplus!#; terpri();
if lplus!#>4 then return aeval 'failed;
z := limsort(cdr ex,x); % ignore car z, a list of 0's.
nrms := caddr z; infs := cadr z;
if length infs>1 then
<<infs := logjoin('plus . infs,x);
infs := if eqcar(infs,'plus) then cdr infs else list infs>>;
% at this point, only infs needs to be evaluated.
vals := for each c in infs collect
minfix prepsq simp!* limit00(simp!* c,x);
z := infs;
for each c in vals do
<<cz := car z; z := cdr z;
if c eq 'infinity then vp := cz . vp
else if c eq '(minus infinity) then vm := cz . vm
else if c eq 'failed then vnix := cz . vnix
else nrms := cz . nrms>>;
if vm and not vp or vp and not vm or length vnix = 1
or length vm > 1 or length vp > 1 then return aeval 'failed;
if vm then vm := qform(car vp,vm);
if vnix then vnix := qform(car vnix,cdr vnix);
vm := append(nrms,append(vm,vnix));
return if null vm then 0 else
limit00(simp!* if length vm>1 then 'plus . vm else car vm,x)
end;
symbolic procedure minfix v;
if eqcar(v,'minus) and numberp cadr v then -cadr v else v;
symbolic procedure qform(a,b);
list list('quotient,list('plus,1,
list('quotient,if length b = 1 then car b else 'plus . b,a)),
list ('quotient,1,a));
symbolic procedure lhopital(top,bot,xxx,a);
begin scalar limt, limb, nvt, nvb;
nvt := notval(limt := limfix(top,xxx,a));
nvb := notval(limb := limfix(bot,xxx,a));
% possibilities for lims are {failed, infinity, -infinity, bounded,
% nonzero, zero} and each combination of cases has to be handled.
if limt=0 and limb=0 or nvt and nvb then go to lhop;
if specval limt or specval limb then return speccomb(limt,limb);
if limb=0 then return aeval 'infinity; % maybe impossible.
return aeval list('quotient,limt,limb);
lhop: lhop!# := lhop!#+1;
% write "lhop#=",lhop!#; terpri();
if lhop!#>6 then return aeval 'failed;
return limit0(prepsq quotsq(diffsq(simp!* top,xxx),
diffsq(simp!* bot,xxx)),xxx,a) end;
symbolic procedure notval lim;
not lim or infinp prepsq simp!* lim;
symbolic procedure infinp x; member(x,'(infinity (minus infinity)));
symbolic procedure specval lim;
notval lim or lim eq 'bounded;
symbolic procedure speccomb(a,b);
aeval
(if not a or not b or b eq 'bounded then 'failed
else if notval b then 0
else if notval a then
if numberp b then
if b>=0 then a
else if a eq 'infinity then '(minus infinity) else 'infinity
else ((if c then
<<c := prepsq c;
if evalgreaterp(c,0) then cc := 1 else if evallessp(c,0)
then cc := -1;
if cc then c := if a eq 'infinity then 1 else -1;
if cc then
if c*cc = 1 then 'infinity else '(minus infinity)
else {'times,{'sgn,b},a}>> else {'quotient,a,b})
where c=topevalsetsq prepsq simp!* b,cc=nil)
else 'failed);
symbolic procedure limfix(ex,x,a);
(if val then val
else limitest(ex,x,a))
where val=limitset(ex,x,a);
symbolic procedure limitest(ex,x,a);
if ex then if atom ex then if ex eq x then a else ex else
begin scalar y,arg,val;
if eqcar(ex,'expt) then
if cadr ex eq 'e then ex := list('exp,caddr ex)
else return exptest(cadr ex,caddr ex,x,a);
if (y := get(car ex,'fixfn)) then
<<arg := cadr ex; val := limitset(arg,x,a);
return apply1(y,
if val then val else limitest(arg,x,a))>>
else if (y := get(car ex,'limcomb)) then
return apply3(y,cdr ex,x,a) end;
symbolic procedure exptest(b,n,x,a);
if numberp n then
if n<0 then limquot1(1,exptest(b,-n,x,a))
else if n=0 then 1 else
((if 2*y=n then limlabs limitest(b,x,a) else limitest(b,x,a))
where y=n/2)
else if numberp b and b>1 then limitest(list('exp,n),x,a);
symbolic procedure limlabs a;
if null a then nil
else if infinp a then 'infinity
else if a eq 'bounded then 'bounded else
begin scalar n,d; d := denr(n := simp!* a); n := numr n;
return if null n then a else if not numberp n then nil
else mk!*sq abs a ./ d end;
symbolic procedure limplus(exl,x,a);
if null exl then 0
else limplus1(mkalg limfix(car exl,x,a),limplus(cdr exl,x,a));
symbolic procedure limplus1(a,b);
if null a or null b then nil
else if infinp a
then if infinp b
then if a eq b then a else nil else a
else if infinp b then b
else if a eq 'bounded or b eq 'bounded then 'bounded
else mk!*sq addsq(simp!* a,simp!* b);
symbolic procedure limtimes(exl,x,a);
if null exl then 1
else ltimes1(mkalg limfix(car exl,x,a),limtimes(cdr exl,x,a));
symbolic procedure mkalg x;
minfix if eqcar(x,'!*sq) then prepsq simp!* x else x;
symbolic procedure ltimes1(a,b);
begin scalar c;
return if null a or null b then nil
else if infinp a then
if infinp b then
if a = b then 'infinity else '(minus infinity)
else if b eq 'bounded or b=0 then nil
else if (c := limposp b) eq 'failed then nil
else if c then a else lminus1 a
else if infinp b then
if a eq 'bounded or a=0 then nil
else if (c := limposp a) eq 'failed then nil
else if c then b else lminus1 b
else if a eq 'bounded or b eq 'bounded then 'bounded
else mk!*sq multsq(simp!* a,simp!* b) end;
symbolic procedure limposp a;
(if n and not numberp n then 'failed else n and n>0)
where n=numr simp!* a;
symbolic procedure lminus(exl,x,a);
lminus1 mkalg limfix(car exl,x,a);
symbolic procedure lminus1 a; if a then
if a eq 'infinity then '(minus infinity)
else if a eq '(minus infinity) then 'infinity
else if a eq 'bounded then a
else mk!*sq negsq simp!* a;
symbolic procedure limquot(exl,x,a);
limquot1(mkalg limfix(car exl,x,a),mkalg limfix(cadr exl,x,a));
symbolic procedure limquot1(a,b);
begin scalar c;
return if null a or null b then nil
else if infinp a then
if infinp b then nil
else if b eq 'bounded then nil
else if b=0 then a
else if (c := limposp b) eq 'failed then nil
else if c then a else lminus1 a
else if infinp b then 0
else if a eq 'bounded then if b=0 then nil else 'bounded
else if b=0 or b eq 'bounded then nil
else mk!*sq quotsq(simp!* a,simp!* b) end;
put('log,'fixfn,'fixlog);
put('sin,'fixfn,'fixsin);
put('cos,'fixfn,'fixsin);
put('sqrt,'fixfn,'fixsqrt);
put('cosh,'fixfn,'fixcosh);
put('sinh,'fixfn,'fixsinh);
put('exp,'fixfn,'fixexp);
put('plus,'limcomb,'limplus);
put('minus,'limcomb,'lminus);
put('times,'limcomb,'limtimes);
put('quotient,'limcomb,'limquot);
symbolic procedure fixlog x;
if zerop x then '(minus infinity) else if infinp x then 'infinity;
symbolic procedure fixsqrt x;
if zerop x then 0 else if infinp x then 'infinity;
symbolic procedure fixsin x;
if infinp x then 'bounded;
symbolic procedure fixcosh x;
if infinp x then 'infinity;
symbolic procedure fixsinh x;
if infinp x then x;
symbolic procedure fixexp x;
if x eq 'infinity then x else if x = '(minus infinity) then 0;
endmodule;
module pf; % Compute partial fractions for an expression.
% Author: Anthony C. Hearn.
Comment PF is the top level operator for finding the partial fractions
of an expression. It returns the partial fractions as a list.
The algorithms used here are relatively unsophisticated, and use the
extended Euclidean algorithm to break up expressions into factors.
Much more sophisticated algorithms exist in the literature;
fluid '(!*exp !*limitedfactors !*gcd kord!*);
symbolic operator pf;
flag('(pf),'noval); % Since PF will do its own simplification.
symbolic procedure pf(u,var);
% Convert an algebraic expression into partial fractions.
begin scalar !*exp,!*gcd,kord!*,!*limitedfactors,polypart,rfactor,
u1,u2,u3,u4,var,x,xx,y;
!*exp := !*gcd := t;
xx := updkorder var; % Make var the main variable.
x := subs2 resimp simp!* u; % To allow for OFF EXP forms.
u1 := denr x;
if degr(u1,var) = 0 then <<setkorder xx; return list('list,u)>>;
u2 := qremsq(!*f2q numr x,!*f2q u1,var); %Extract polynomial part.
if caar u2 then polypart := car u2;
rfactor := 1 ./ 1; % Factor for rational part.
u2 := cdr u2;
u3 := fctrf u1; % Factorize denominator.
x := cdr u3;
u3 := car u3;
% Process monomial part.
while not domainp u3 do
<<if mvar u3 eq var then x := (!*k2f mvar u3 . ldeg u3) . x
else <<u4 := !*p2f lpow u3;
rfactor := numr rfactor ./ multf(u4,denr rfactor);
u1 := quotf(u1,u4)>>;
u3 := lc u3>>;
if u3 neq 1 then <<rfactor := numr rfactor
./ multf(u3,denr rfactor);
u1 := quotf(u1,u3)>>;
% Separate power factors in denominator.
while length x>1 do
<<u3 := exptf(caar x,cdar x);
u1 := quotf(u1,u3);
if degr(u3,var)=0
then <<rfactor := numr rfactor ./ multf(u3,denr rfactor);
u2 := nil>>
else <<u4 := xeucl(u1,u3,var);
% Remove spurious polynomial in numerator.
y := (remsq(multsq(car u4,u2),!*f2q u3,var) . car x)
. y;
u2 := multsq(cdr u4,u2)>>;
x := cdr x>>;
u3 := exptf(caar x,cdar x);
if u2 = (nil ./ 1) then nil
else if degr(u3,var)=0
then rfactor := numr rfactor ./ multf(u3,denr rfactor)
% Remove spurious polynomial in numerator.
else y := (remsq(u2,!*f2q u3,var) . car x) . y;
x := nil;
% Finally break down non-linear terms in denominator.
for each j in y do
if cddr j =1 then x := j . x
else x := append(pfpower(car j,cadr j,cddr j,var),x);
% Fold in rfactor.
if rfactor neq '(1 . 1)
then x := for each j in x
collect multsq(rfactor,car j) . cdr j;
x := for each j in x
collect list('quotient,prepsq!* car j,
if cddr j=1 then prepf cadr j
else list('expt,prepf cadr j,cddr j));
if polypart then x := prepsq!* polypart . x;
setkorder xx;
return 'list . x
end;
symbolic procedure xeucl(u,v,var);
% Extended Euclidean algorithm with rational coefficients.
% I.e., find polynomials Q, R in var with rational coefficients (as
% standard quotients) such that Q*u + R*v = 1, where u and v are
% relatively prime standard forms in variable var. Returns Q . R.
begin scalar q,r,s,w;
q := list(1 ./ 1,nil ./ 1);
r := list(nil ./ 1,1 ./ 1);
if degr(u,var) < degr(v,var)
then <<s := u; u := v; v := s; s := q; q := r; r := s>>;
u := !*f2q u; v := !*f2q v;
while numr v do
<<if degr(numr v,var)=0 then w := quotsq(u,v) . (nil ./ 1)
else w := qremsq(u,v,var);
s := list(addsq(car q,negsq multsq(car w,car r)),
addsq(cadr q,negsq multsq(car w,cadr r)));
u := v;
v := cdr w;
q := r;
r := s>>;
v := lnc numr u ./ denr u; % Is it possible for this not to be
% in lowest terms, and, if so, does
% it matter?
r := quotsq(v,u);
return multsq(r,quotsq(car q,v)) . multsq(r,quotsq(cadr q,v))
end;
symbolic procedure qremsq(u,v,var);
% Find rational quotient and remainder (as standard quotients)
% dividing standard quotients u by v wrt var.
% This should really be done more directly without using quotsq.
(quotsq(addsq(u,negsq x),v) . x) where x=remsq(u,v,var);
symbolic procedure remsq(u,v,var);
% Find rational and remainder (as a standard quotient) on
% dividing standard quotients u by v wrt var.
begin integer m,n; scalar x;
n := degr(numr v,var);
if n=0 then rederr list "Remsq given zero degree polynomial";
while (m := degr(numr u,var))>= n do
<<if m=n then x := v
else x := multsq(!*p2q(var.**(m-n)),v);
u := addsq(u,
negsq multsq(multf(lc numr u,denr v)
./ multf(lc numr v,denr u),
x))>>;
return u
end;
symbolic procedure pfpower(u,v,n,var);
% Convert u/v^n into partial fractions.
begin scalar x,z;
while degr(numr u,var)>0 do
<<x := qremsq(u,!*f2q v,var);
z := (cdr x . v . n) . z;
n := n-1;
u := car x>>;
if numr u then z := (u . v . n) . z;
return z
end;
endmodule;
module sum; % Package for summation in finite terms.
% Authors: K.Yamamoto, K.Kishimoto & K.Onaga Hiroshima Univ.
% Modified by: F.Kako Hiroshima Univ.
% Fri Sep. 19, 1986
% Mon Sep. 7, 1987 added PROD operator (by F. Kako)
% e-mail: kako@kako.math.sci.hiroshima-u.ac.jp
% or D52789%JPNKUDPC.BITNET
% Usage:
% sum(expression,variable[,lower[,upper]]);
% lower and upper are optionals.
% prod(expression,variable[,lower[,upper]]);
% returns product of expression.
fluid '(!*trsum); % trace switch;
switch trsum;
symbolic procedure simp!-sum u;
%ARGUMENT CAR U: expression of prefix form;
% CADR U: kernel;
% CADDR U: lower bound;
% CADDDR U: upper bound;
%value : expression of sq form;
begin scalar v,y,upper,lower,lower1,dif;
y := cdr u;
u := simp!* car u;
if null numr u then return (nil ./ 1)
else if atom y then return u;
if not atom cdr y then <<
lower := cadr y;
lower1 := if numberp lower then lower - 1
else list('plus,lower,-1);
upper := if not atom cddr y then caddr y else car y;
dif := addsq(simp!* upper, negsq simp!* lower);
if denr dif = 1 then
if null numr dif then return u
else if fixp numr dif then dif := numr dif
else dif := nil
else dif := nil;
if dif and dif <= 0 then return nil ./ 1;
if atom cddr y then upper := nil>>;
v := !*a2k car y;
return simp!-sum1(u,v,y,upper,lower,lower1,dif)
end;
symbolic procedure simp!-sum1(u,v,y,upper,lower,lower1,dif);
begin scalar w,lst,x,z,flg;
lst := sum!-split!-log(u,v);
w := car lst;
lst := cdr lst;
u := nil ./ 1;
a:
if null w then go to b;
x := multsq(caar w,
simp!-prod1(cdar w,v,y,upper,lower,lower1,dif));
u := addsq(u,simp!* list('log, prepsq x));
w := cdr w;
go to a;
b:
if null lst then return u;
flg := nil;
z := car lst;
if !*trsum then <<
prin2!* "Summation ";sqprint z;prin2!* " w.r.t ";
xprinf(!*k2f v,nil,nil);terpri!* t >>;
% z := reorder numr z ./ reorder denr z;
w := sum!-sq(z,v);
if w = 'failed then <<
if !*trsum then <<
prin2!* "UMM-SQ failed. Trying SUM-TRIG";
terpri!* t>>;
w := sum!-trig(z,v);
if w = 'failed then <<
if !*trsum then <<
prin2!* "SUM-TRIG failed.";
terpri!* t>>;
w := sum!-unknown(z,v,y,lower,dif);
flg := car w;
w := cdr w>>>>;
if !*trsum then <<
prin2!* "Result = "; sqprint w; terpri!* t >>;
if flg then goto c;
if upper then
w := addsq(subsq(w,list(v . upper)),
negsq subsq(w,list(v . lower1)))
else if lower then
w := addsq(w , negsq subsq(w, list(v . lower1)));
c:
u := addsq(u,w);
lst := cdr lst;
goto b
end;
put('sum,'simpfn,'simp!-sum);
%*********************************************************************
% Case of trigonometric or other functions
% Trigonometric functions are expressed in terms of exponetials.
% Pattern matching to get the summation in closed form.
%********************************************************************;
global '(!*trig!-to!-exp); % variable to indicate
% that the expression contains
% some trig. functions.
symbolic procedure sum!-trig(u,v);
begin scalar lst,w; % z;
!*trig!-to!-exp := nil; % trig. to exponential.
u := trig!-to!-expsq(u,v);
if not !*trig!-to!-exp then return 'failed;
lst := sum!-term!-split(u,v);
u := nil ./ 1;
a:
if null lst then return exp!-to!-trigsq u;
% z := reorder numr car lst ./ reorder denr car lst;
% w := sum!-sq(z,v);
w := sum!-sq(car lst,v);
if w = 'failed then return 'failed;
% w := exp!-to!-trigsq w; % exponential to trig. function.
u := addsq(u,w);
lst := cdr lst;
goto a
end;
symbolic procedure sum!-unknown(u,v,y,lower,dif);
begin scalar z,w;
if null dif then <<
z := 'sum . (prepsq u . list car y);
if w := opmtch z then return (nil . simp w)
else if null cdr y then return (t . mksq(z,1));
z := 'sum . (prepsq u . y);
return (t . if w := opmtch z then simp w else mksq(z,1))>>;
z := nil ./ 1;
a:
if dif < 0 then return (t . z);
z := addsq(z,subsq(u,list(v . list('plus,lower,dif))));
dif := dif - 1;
goto a
end;
%*********************************************************************
% Summation by Gosper's algorithm.
%********************************************************************;
symbolic procedure sum!-sq(u,v);
%Argument U : expression of s-q;
% V : kernel;
%value : expression of sq (result of summation.);
begin scalar gn,fn,pn,rn,qn,z,k,x;
if null numr u then return nil ./ 1;
x := setkorder list v;
z := reorder numr u;
u := z ./ reorder denr u;
if !*trsum then <<
prin2t " *** Summation by Gosper's algorithm ***";
prin2!* " A(n) = "; sqprint u;terpri!* t;
terpri!* t>>;
if domainp z or not (mvar z eq v) or red z then
<<pn := 1; z := u>>
else <<pn := !*p2f lpow z;
z := lc z ./ denr u>>;
z := quotsq(z,nsubsq(z,v, - 1));
gn := gcdf!*(numr z,denr z);
if !*trsum then <<
prin2!* "A(n)/A(n-1) = ";sqprint z;terpri!* t;
prin2!* "GN = ";xprinf(gn,nil,nil);terpri!* t>>;
qn := quotf!*(numr z, gn);
rn := quotf!*(denr z, gn);
if nonpolyp(qn,v) or nonpolyp(rn,v) then go to fail;
if !*trsum then <<
prin2!* "Initial qn, rn and pn are "; terpri!* t;
prin2!* "QN = ";xprinf(qn,nil,nil);terpri!* t;
prin2!* "RN = ";xprinf(rn,nil,nil);terpri!* t;
prin2!* "PN = ";xprinf(pn,nil,nil);terpri!* t>>;
k := compress explode '!+j;
z := integer!-root(resultant(qn,nsubsf(rn,v,k),v),k);
if !*trsum then <<
prin2 "Root of resultant(q(n),r(n+j)) are "; prin2t z >>;
while z do <<
k := car z;
gn := gcdf!*(qn,nsubsf(rn,v,k));
qn := quotf!*(qn,gn);
rn := quotf!*(rn,nsubsf(gn,v, -k));
while (k := k - 1)>=0 do
pn := multf(pn,nsubsf(gn,v, -k));
z := cdr z>>;
if !*trsum then <<
prin2!* "Shift free qn, rn and pn are";terpri!* t;
prin2!* "QN = ";xprinf(qn,nil,nil);terpri!* t;
prin2!* "RN = ";xprinf(rn,nil,nil);terpri!* t;
prin2!* "PN = ";xprinf(pn,nil,nil);terpri!* t>>;
qn := nsubsf(qn,v,1);
if (k := degree!-bound(pn,addf(qn,rn),addf(qn,negf rn),v)) < 0
then go to fail;
if !*trsum then <<
prin2 "DEGREE BOUND is "; prin2t k >>;
if not(fn := solve!-fn(k,pn,qn,rn,v)) then go to fail;
if !*trsum then <<
prin2!* "FN = ";sqprint fn;terpri!* t >>;
u := multsq(multsq(qn ./ 1,fn), multsq(u, 1 ./ pn));
z := gcdf!*(numr u, denr u);
u := quotf!*(numr u, z) ./ quotf!*(denr u,z);
if !*trsum then <<
prin2t " *** Gosper's algorithm completed ***";
prin2!* " S(n) = "; sqprint u;terpri!* t;
terpri!* t>>;
setkorder x;
return (reorder numr u ./ reorder denr u);
fail:
if !*trsum then <<
prin2t " *** Gosper's algorithm failed ***";
terpri!* t>>;
setkorder x;
return 'failed
end;
%*********************************************************************
% integer root isolation
%********************************************************************;
symbolic procedure integer!-root(u,v);
% Produce a list of all positive integer root of U;
begin scalar x,root,n,w;
x := setkorder list v;
u := reorder u;
if domainp u or not(mvar u eq v) then go to a;
u := numr cancel(u ./ lc u);
w := u; % get trailing term;
while not domainp w and mvar w eq v and cdr w do
w := cdr w;
if (n := degr(w,v)) > 0 then <<
w := lc w;
while n > 0 do <<
root := 0 . root;
n := n - 1>>>>;
n := dfactors lowcoef w; % factor tail coeff.
w := (v . 1) . 1;
while n do <<
if not testdivide(u,v,car n) then <<
root := car n . root;
u := quotf!*(u, (w . - car n))>>
else n := cdr n>>;
a:
setkorder x;
return root
end;
symbolic procedure lowcoef u;
begin scalar lst,m;
lst := dcoefl u;
m := 0;
a:
if null lst then return m;
m := gcdn(m,car lst);
if m = 1 then return 1;
lst := cdr lst;
go to a
end;
symbolic procedure dcoefl u;
if domainp u then if fixp u then list abs u else nil
else nconc(dcoefl lc u , dcoefl red u);
symbolic procedure testdivide(u,v,n);
% Evaluate U at integer point (V = N);
begin scalar x;
a:
if domainp u or not(mvar u eq v) then return addf(u,x);
x := addf(multd(expt(n,ldeg u),lc u),x);
if (u := red u) then go to a;
return x
end;
%*********************************************************************
%********************************************************************;
symbolic procedure degree!-bound(pn,u,v,kern);
% degree bound for fn;
% u: q(n+1) + r(n);
% v: q(n+1) - r(n);
begin scalar lp,l!+, l!-, x,m,k;
x := setkorder list kern;
u := reorder u;
v := reorder v;
pn := reorder pn;
l!+ := if u then degr(u,kern) else -1;
l!- := if v then degr(v,kern) else -1;
lp := if pn then degr(pn,kern) else -1;
if l!+ <= l!- then <<k := lp - l!-;go to a>>;
k := lp - l!+ + 1;
if l!+ > 0 then u := lc u;
if l!- > 0 then v := lc v;
if l!+ = l!- + 1 and fixp(m := quotf1(multd(-2,v),u)) then
k := max(m,k)
else if lp = l!- then k := max(k,0);
a:
setkorder x;
return k
end;
%*********************************************************************
% calculate polynomial f(n) such that
% p(n) - q(n+1)*f(n) + r(n)*f(n-1) = 0;
%********************************************************************;
symbolic procedure solve!-fn(k,pn,qn,rn,v);
begin scalar i,fn,x,y,z,u,w,c,clst,flst;
c := makevar('c,0);
clst := list c;
fn := !*k2f c;
i := 0;
while (i := i + 1) <= k do <<
c := makevar('c,i);
clst := c . clst;
fn := ((v . i) . !*k2f c) . fn>>;
z :=
addf(pn,
addf(negf multf(qn,fn),
multf(rn,nsubsf(fn,v, - 1))));
x := setkorder (v . clst);
z := reorder z;
c := clst;
if !*trsum then <<
prin2!* "C Equation is";terpri!* t;
xprinf(z,nil,nil);terpri!* t >>;
a:
if domainp z or
domainp (y := if mvar z eq v then lc z else z) then
go to fail;
w := mvar y;
if not(w memq clst) then go to fail;
if !*trsum then <<
prin2!* "C Equation to solve is ";xprinf(y,nil,nil);terpri!* t;
prin2!* " w.r.t ";xprinf(!*k2f w,nil,nil);terpri!* t >>;
u := gcdf!*(red y , lc y);
u := quotf!*(negf red y, u) ./ quotf!*(lc y, u);
flst := (w . u) . flst;
z := subst!-cn(z,w,u);
if !*trsum then <<
xprinf(!*k2f w,nil,nil);prin2!* " := ";sqprint u;terpri!* t >>;
clst := deleteq(clst,w);
if z then go to a;
setkorder c;
fn := reorder fn;
u := 1;
while not domainp fn and mvar fn memq c do <<
w := mvar fn;
z := atsoc(w,flst);
fn := subst!-cn(fn,w,if z then cdr z);
if z then u := multf(u,denr cdr z);
z := gcdf!*(fn,u);
fn := quotf!*(fn,z);
u := quotf!*(u,z)>>;
setkorder x;
return cancel(reorder fn ./ reorder u);
fail:
if !*trsum then <<
prin2t "Fail to solve C equation.";
prin2!* "Z := ";xprinf(z,nil,nil);terpri!* t >>;
setkorder x;
return nil
end;
symbolic procedure subst!-cn(u,v,x);
begin scalar z;
z := setkorder list v;
u := reorder u;
if not domainp u and mvar u eq v then
if x then u := addf(multf(lc u,reorder numr x),
multf(red u,reorder denr x))
else u := red u;
setkorder z;
return reorder u
end;
symbolic procedure makevar(id,n);
compress nconc(explode id, explode n);
symbolic procedure deleteq(u,x);
if null u then nil
else if car u eq x then cdr u
else car u . deleteq(cdr u, x);
symbolic procedure nsubsf(u,kern,i);
% ARGUMENT U : expression of sf;
% KERN : kernel;
% I : integer or name of integer variable;
% value : expression of sf;
begin scalar x,y,z,n;
if null i or i = 0 then return u;
x := setkorder list kern;
u := reorder u;
y := addf(!*k2f kern,
if fixp i then i else !*k2f i);
z := nil;
a:
if domainp u or not(mvar u eq kern) then goto b;
z := addf(z,lc u);
n := degr(u,kern) - degr(red u,kern);
u := red u;
a1:
if n <= 0 then goto a;
z := multf(z,y);
n := n - 1;
go to a1;
b:
z := addf(z,u);
setkorder x;
return reorder z
end;
symbolic procedure nsubsq(u,kern,i);
% ARGUMENT U : expression of sq;
% KERN : kernel;
% I : integer or name of integer variable;
% value : expression of sq;
subsq(u,list(kern . list('plus, kern, i)));
%*********************************************************************
% dependency check
%********************************************************************;
symbolic procedure nonpolyp(u,v);
% check U is not a polynomial of V;
if domainp u then nil
else (not(mvar u eq v) and depend!-p(mvar u,v))
or nonpolyp(lc u,v) or nonpolyp(red u,v);
symbolic procedure depend!-sq(u,v);
depend!-f(numr u,v) or depend!-f(denr u,v);
symbolic procedure depend!-f(u,v);
if domainp u then nil
else depend!-p(mvar u,v) or
depend!-f(lc u,v) or
depend!-f(red u,v);
symbolic procedure depend!-p(u,v);
if u eq v then t
else if atom u then nil
else if not atom car u then depend!-f(u,v)
else if car u eq '!*sq then depend!-sq(cadr u, v)
else depend!-l(cdr u, v);
symbolic procedure depend!-l(u,v);
if null u then nil
else if depend!-sq(simp car u, v) then t
else depend!-l(cdr u,v);
%*********************************************************************
% term splitting
%********************************************************************;
symbolic procedure sum!-term!-split(u,v);
begin scalar y,z,klst,lst,x;
x := setkorder list v;
z := qremf(reorder numr u, y := reorder denr u);
klst := kern!-list(car z,v);
lst := termlst(car z, 1 ./ 1, klst);
klst := kern!-list(cdr z,v);
if depend!-f(y,v) then klst := deleteq(klst,v);
lst := append(lst, termlst(cdr z, 1 ./ y, klst));
setkorder x;
return lst
end;
symbolic procedure kern!-list(u,v);
% Returns list of kernels that depend on V;
begin scalar x;
for each j in kernels u do if depend!-p(j,v) then x := j . x;
return x
end;
symbolic procedure termlst(u,v,klst);
begin scalar x,kern,lst;
if null u then return nil
else if null klst or domainp u then
return list multsq(!*f2q u,v);
kern := car klst;
klst := cdr klst;
x := setkorder list kern;
u := reorder u;
v := reorder(numr v) ./ reorder(denr v);
while not domainp u and mvar u eq kern do <<
lst := nconc(termlst(lc u, multsq(!*p2q lpow u, v),klst),lst);
u := red u>>;
if u then lst := nconc(termlst(u,v,klst),lst);
setkorder x;
return lst
end;
%*********************************************************************
% Express trigonometric functions (such as sin, cos ..)
% by exponentials.
%********************************************************************;
symbolic procedure trig!-to!-expsq(u,v);
multsq(trig!-to!-expf(numr u,v),
invsq trig!-to!-expf(denr u,v));
symbolic procedure trig!-to!-expf(u,v);
if domainp u then u ./ 1
else addsq(multsq(trig!-to!-expp(lpow u,v),
trig!-to!-expf(lc u,v)),
trig!-to!-expf(red u,v));
symbolic procedure trig!-to!-expp(u,v);
begin scalar w,x,z,n,wi;
n := cdr u; % integer power;
z := car u; % main variable;
if atom z or not atom (x := car z) or not depend!-p(z,v) then
return !*p2q u;
if x memq '(sin cos tan sec cosec cot) then <<
!*trig!-to!-exp := t;
w := multsq(!*k2q 'i, simp!* cadr z);
w := simp!* list('expt,'e, mk!*sq w);
% W := SIMP LIST('EXPT,'E, 'TIMES . ( 'I . CDR Z));
wi := invsq w;
if x eq 'sin then
w := multsq(addsq(w ,negsq wi),
1 ./ list(('i .** 1) .* 2))
else if x eq 'cos then
w := multsq(addsq(w, wi), 1 ./ 2)
else if x eq 'tan then
w := multsq(addsq(w,negsq wi),
invsq addsq(w,wi))
else if x eq 'sec then
w := multsq(2 ./ 1, invsq addsq(w, wi))
else if x eq 'cosec then
w := multsq(list(('i .** 1) .* 2),
invsq addsq(w, negsq wi))
else
w := multsq(addsq(w, wi),
invsq addsq(w, negsq wi))
>>
else if x memq '(sinh cosh tanh sech cosech coth) then <<
!*trig!-to!-exp := t;
w := simp!* list('expt,'e,cadr z);
wi := invsq w;
if x eq 'sinh then
w := multsq(addsq(w,negsq wi), 1 ./ 2)
else if x eq 'cosh then
w := multsq(addsq(w,wi), 1 ./ 2)
else if x eq 'tanh then
w := multsq(addsq(w,negsq wi),
invsq addsq(w,wi))
else if x eq 'sech then
w := multsq(2 ./ 1, invsq addsq(w, wi))
else if x eq 'cosech then
w := multsq(2 ./ 1, invsq addsq(w, negsq wi))
else
w := multsq(addsq(w,wi),
invsq addsq(w, negsq wi))
>>
else return !*p2q u;
return exptsq(w,n)
end;
%*********************************************************************
% Inverse of trig!-to!-exp.
% Express exponentials in terms of trigonometric functions
% (sin, cos, sinh and cosh)
% Wed Dec. 17, 1986 by F. Kako;
%********************************************************************;
symbolic procedure exp!-to!-trigsq u;
multsq(exp!-to!-trigf numr u,
invsq exp!-to!-trigf denr u);
symbolic procedure exp!-to!-trigf u;
begin scalar v,v1,x,y,n;
u := termlst1(u,1,nil ./1);
v := nil;
a:
if null u then go to b;
x := caar u;
y := cdar u;
u := cdr u;
a1:
if u and y = cdar u then <<
x := addf(x,caar u);
u := cdr u;
go to a1>>;
v := (x . y) . v;
go to a;
b:
v1 := reverse v;
n := length v;
u := nil ./ 1;
c:
if n = 0 then return u
else if n = 1 then
return addsq(u,
multsq(!*f2q caar v,
simp!* list('expt,'e,mk!*sq cdar v)));
u := addsq(u,exp!-to!-trigl(caar v1,caar v,cdar v1,cdar v));
v := cdr v;
v1 := cdr v1;
n := n - 2;
go to c
end;
symbolic procedure exp!-to!-trigl(a,b,c,d);
% A*E**C + B*E**D
% -->
% ((A+B)*COSH((C-D)/2)+(A-B)*SINH((C-D)/2))*E**((C+D)/2);
% A, B: sf;
% C, D: sq;
begin scalar x,y,z;
x := !*f2q addf(a,b);
y := !*f2q addf(a, negf b);
z := multsq(addsq(c,negsq d), 1 ./ 2);
z := real!-imag!-sincos z;
return multsq(simp!* list('expt,'e,
mk!*sq multsq(addsq(c,d),1 ./ 2)),
addsq(multsq(x, cdr z),
multsq(y, car z)))
end;
symbolic procedure termlst1(u,v,w);
%ARGUMENT U : sf;
% V : sf;
% W : sq;
%value : list of (sf . sq);
begin scalar x,y;
if null u then return nil
else if domainp u then return list (multf(u,v) . w);
x := mvar u;
y := if atom x or not(car x eq 'expt) or not(cadr x eq 'e) then
termlst1(lc u,multf(!*p2f lpow u,v),w)
else termlst1(lc u,v,addsq(w,multsq(simp!* caddr x,
ldeg u ./ 1)));
return nconc(y,termlst1(red u,v,w))
end;
%*********************************************************************
% Module --- COMPLEX;
% Wed Dec. 17, 1986 by F. Kako;
%********************************************************************;
%******************************************************************
%******* SPLIT REAL AND IMAGINARY PART ******************
%******************************************************************
symbolic procedure real!-imag!-sq u;
%U is a standard quotient,
%Value is the standard quotient real part and imaginary part of U.
begin scalar x,y;
x := real!-imag!-f numr u;
y := real!-imag!-f denr u;
u := addf(multf(car y, car y),
multf(cdr y, cdr y)); % Re Y **2 + Im Y **2;
return (cancel(addf(multf(car x, car y),
multf(cdr x, cdr y))
./ u) .
cancel(addf(multf(car y, cdr x),
negf multf(car x, cdr y))
./ u))
end;
symbolic procedure real!-imag!-f u;
%U is a standard form.
%Value is the standard form real and imag part of U.
begin scalar x;
if domainp u then return u . nil;
x := setkorder list 'i;
u := reorder u;
u := if mvar u eq 'i and ldeg u = 1 then red u . lc u
else u . nil;
setkorder x;
return (reorder car u . reorder cdr u)
end;
%*****************************************************************
% hyperbolic functions
%*****************************************************************;
symbolic procedure real!-imag!-sincos u;
begin scalar v,w,z;
v := real!-imag!-sq u;
if null cadr v then <<
u := prepsq u;
return simp!* list('sinh,u)
. simp!* list('cosh,u)>>
else if null caar v then <<
u := prepsq cdr v;
return (multsq(!*k2q 'i, simp!* list('sin,u))
. simp!* list('cos,u))>>;
u := prepsq cdr v;
v := prepsq car v;
w := simp!* list('cos,u);
u := simp!* list('sin,u);
u := multsq(!*k2q 'i,u);
z := simp!* list('cosh,v);
v := simp!* list('sinh,v);
return (addsq (multsq(w, v), multsq(u,z)))
. (addsq (multsq(w,z),multsq(u,v)))
end;
%*********************************************************************
% module --- product
% package for production in finite terms
%
% Author: F.Kako Hiroshima Univ.
% Mon Sep. 7, 1987
%
% usage:
% prod(expression,variable[,lower[,upper]]);
% lower and upper are optionals;
%
%
%********************************************************************;
%*********************************************************************
%********************************************************************;
symbolic procedure simp!-prod u;
%ARGUMENT CAR U: expression of prefix form;
% CADR U: kernel;
% CADDR U: lower bound;
% CADDDR U: upper bound;
%value : expression of sq form;
begin scalar v,y,upper,lower,lower1,dif;
y := cdr u;
u := simp!* car u;
if null numr u then return (1 ./ 1)
else if atom y then return u;
if not atom cdr y then <<
lower := cadr y;
lower1 := if numberp lower then lower - 1
else list('plus,lower,-1);
upper := if not atom cddr y then caddr y else car y;
dif := addsq(simp!* upper, negsq simp!* lower);
if denr dif = 1 then
if null numr dif then return u
else if fixp numr dif then dif := numr dif
else dif := nil
else dif := nil;
if dif and dif <= 0 then return 1 ./ 1;
if atom cddr y then upper := nil>>;
v := !*a2k car y;
return simp!-prod1(u,v,y,upper,lower,lower1,dif)
end;
symbolic procedure simp!-prod1(u,v,y,upper,lower,lower1,dif);
begin scalar w,lst,x,z,flg;
lst := prod!-split!-exp(u,v);
w := car lst;
lst := cdr lst;
u := 1 ./ 1;
a:
if null w then go to b;
x := simp!-sum1(cdar w,v,y,upper,lower,lower1,dif);
u := multsq(u,simpexpt list(caar w, prepsq x));
w := cdr w;
go to a;
b:
if null lst then return u;
flg := nil;
z := car lst;
if !*trsum then <<
prin2!* "Product ";sqprint z;prin2!* " w.r.t ";
xprinf(!*k2f v,nil,nil);terpri!* t >>;
% z := reorder numr z ./ reorder denr z;
w := prod!-sq(z,v);
if w = 'failed then <<
if !*trsum then <<
prin2!* "PROD-SQ failed.";
terpri!* t>>;
w := prod!-unknown(z,v,y,lower,dif);
flg := car w;
w := cdr w>>;
if !*trsum then <<
prin2!* "Result = "; sqprint w;terpri!* t >>;
if flg then goto c;
if upper then
w := multsq(subsq(w,list(v . upper)),
invsq subsq(w,list(v . lower1)))
else if lower then
w := multsq(w , invsq subsq(w, list(v . lower1)));
c:
u := multsq(u,w);
lst := cdr lst;
goto b
end;
put('prod,'simpfn,'simp!-prod);
%*********************************************************************
% Case of other functions
%********************************************************************;
symbolic procedure prod!-unknown(u,v,y,lower,dif);
begin scalar z,w;
if null dif then <<
z := 'prod . (prepsq u . list car y);
if w := opmtch z then return (nil . simp w)
else if null cdr y then return (t . mksq(z,1));
z := 'prod . (prepsq u . y);
return (t . if w := opmtch z then simp w else mksq(z,1))>>;
z := 1 ./ 1;
a:
if dif < 0 then return (t . z);
z := multsq(z,subsq(u,list(v . list('plus,lower,dif))));
dif := dif - 1;
goto a
end;
%*********************************************************************
% Product of rational function
%********************************************************************;
symbolic procedure prod!-sq(u,v);
%ARGUMENT U : expression of s-q;
% V : kernel;
%value : expression of sq (result of product.);
begin scalar gn,p1n,p2n,rn,qn,z,k,x,y;
if null numr u then return 1 ./ 1;
x := setkorder list v;
qn := reorder numr u;
rn := reorder denr u;
if !*trsum then <<
prin2t " *** Product of A(n) = qn/rn with ***";
prin2!* "QN = ";xprinf(qn,nil,nil);terpri!* t;
prin2!* "RN = ";xprinf(rn,nil,nil);terpri!* t>>;
if nonpolyp(qn,v) or nonpolyp(rn,v) then go to fail;
k := compress explode '!+j;
z := integer!-root2(resultant(qn,nsubsf(rn,v,k),v),k);
if !*trsum then <<
prin2 "Root of resultant(q(n),r(n+j)) are "; prin2t z >>;
p2n := p1n := 1;
while z do <<
k := car z;
gn := gcdf!*(qn,nsubsf(rn,v,k));
qn := quotf!*(qn,gn);
rn := quotf!*(rn,nsubsf(gn,v, -k));
if k > 0 then
while (k := k - 1)>=0 do <<
p1n := multf(p1n,nsubsf(gn,v, -k));
if y := prod!-nsubsf(gn,v,-k)
then p2n := multf(p2n,y)>>
else if k < 0 then
while k < 0 do <<
p2n := multf(p2n,nsubsf(gn,v, -k));
if y := prod!-nsubsf(gn,v,-k)
then p1n := multf(p1n,y);
k := k + 1>>;
z := cdr z>>;
if depend!-f(qn,v) or depend!-f(rn,v) then go to fail;
u := multsq(p1n ./ p2n, simpexpt list(prepsq (qn ./ rn), v));
if !*trsum then <<
prin2t " *** Product of rational function calculated ***";
prin2!* " P(n) = "; sqprint u;terpri!* t;
terpri!* t>>;
setkorder x;
return (reorder numr u ./ reorder denr u);
return u;
fail:
if !*trsum then <<
prin2t " *** Product of rational function failed ***";
terpri!* t>>;
setkorder x;
return 'failed
end;
symbolic procedure prod!-nsubsf(u,kern,i);
% ARGUMENT U : expression of sf;
% KERN : kernel;
% I : integer;
% value : expression of sf;
begin scalar x,z,n;
x := setkorder list kern;
u := reorder u;
z := nil;
a:
if domainp u or not(mvar u eq kern) then goto b;
z := addf(z,lc u);
n := degr(u,kern) - degr(red u,kern);
u := red u;
if i = 0 then if n = 0 then nil else z := nil
else z := multf(z,expt(i,n));
go to a;
b:
z := addf(z,u);
setkorder x;
return reorder z
end;
%*********************************************************************
% integer (positive and negative) root isolation
%********************************************************************;
symbolic procedure integer!-root2(u,v);
% Produce a list of all integer root of U;
begin scalar x,root,n,w;
x := setkorder list v;
u := reorder u;
if domainp u or not(mvar u eq v) then go to a;
u := numr cancel(u ./ lc u);
w := u; % get trailing term;
while not domainp w and mvar w eq v and cdr w do
w := cdr w;
if (n := degr(w,v)) > 0 then <<
w := lc w;
while n > 0 do <<
root := 0 . root;
n := n - 1>>>>;
n := dfactors lowcoef w; % factor tail coeff.;
w := (v . 1) . 1;
while n do <<
if not testdivide(u,v,car n) then <<
root := car n . root;
u := quotf!*(u, (w . - car n))>>
else if not testdivide(u,v,- car n) then <<
root := (- car n) . root;
u := quotf!*(u, (w . car n))>>
else n := cdr n>>;
a:
setkorder x;
return root
end;
%*********************************************************************
% log and exponential term splitting for summation and product
%********************************************************************;
symbolic procedure sum!-split!-log(u,v);
begin scalar x,y,z,lst,llst,mlst;
lst := sum!-term!-split(u,v);
a:
if null lst then return (llst. mlst);
u := car lst;
lst := cdr lst;
z := numr u;
if domainp z or red z or not (tdeg (z := lt z) = 1) or
atom tvar z or not ((car tvar z) eq 'log)
or depend!-f(tc z,v) or depend!-f(denr u,v)
then <<mlst := u . mlst;go to a>>;
y := reorder tc z ./ reorder denr u;
z := simp!* cadr tvar z;
if x := assoc(y,llst) then rplacd(x,multsq(cdr x,z))
else if x := assoc(negsq y,llst)
then rplacd(x,multsq(cdr x,invsq z))
else llst := (y . z) . llst;
go to a
end;
symbolic procedure prod!-split!-exp(u,v);
begin scalar x,y,z,w,klst,lst;
% lst := kernels(numr u,nil);
lst := kernels numr u;
% lst := kernels1denr u,lst);
lst := kernels1(denr u,lst);
a:
if null lst then go to b;
z := car lst;
if not atom z and car z eq 'expt and
not depend!-p(cadr z,v) and depend!-p(caddr z,v)
then klst := z . klst;
lst := cdr lst;
go to a;
b:
if null klst then return (nil . list u);
x := setkorder klst;
z := reorder numr u;
y := reorder denr u;
c:
if domainp z or red z or not memq(w := mvar z,klst)
then go to d;
v := multsq(tdeg lt z ./ 1,simp!* caddr w);
w := cadr w;
if u := assoc(w,lst) then rplacd(u,addsq(cdr u,v))
else lst := (w . v) . lst;
z := tc lt z;
go to c;
d:
if domainp y or red y or not memq(w := mvar y,klst)
then go to e;
v := multsq(tdeg lt y ./ 1,negsq simp!* caddr w);
w := cadr w;
if u := assoc(w,lst) then rplacd(u,addsq(cdr u,v))
else lst := (w . v) . lst;
y := tc lt y;
go to d;
e:
setkorder x;
u := reorder z ./ reorder y;
return (lst . list u)
end;
% These can be found in Abramowitz-Stegun (27.8.6 Summable Series), and
% were suggested by Winfried Neun.
algebraic;
let {sum(sin(~n*~tt)/n,~n,1,infinity) => (pi - tt)/2,
sum(sin(~n*~tt)/(~n)^3,~n,1,infinity) =>
pi^2*tt/6 - pi*tt^2/4 + tt^3/12,
sum(sin(~n*~tt)/(~n)^5,~n,1,infinity) =>
pi^4*tt/90 - pi^2*tt^3/36 + pi*tt^4/48-tt^5/240}$
let {sum(cos(~n*~tt)/(~n),~n,1,infinity) => -log(2*sin(tt/2)),
sum(cos(~n*~tt)/(~n)^2,~n,1,infinity) =>
pi^2/6 - pi*tt/2 + tt^2/4,
sum(cos(~n*~tt)/(~n)^4,~n,1,infinity) =>
pi^4/90 - pi^2*tt^2/12 + pi*tt^3/12-tt^4/48}$
endmodule;
end;