File r38/packages/plot/plot.red artifact aad8ee73d2 part of check-in 5f584e9b52

module plot; % device and driver independent plot services.

% Author: Herbert Melenk.
% Adjusted by A C Norman to be compatible with CSL - the original
% was written to be fairly PSL-specific.

% Minor corrections by Winfried Neun (October 1995)

create!-package('(plot plotsynt plotexp2 pltpara plotexp3 plotimp2
                  plotimp3 plotnum parray xvect),
		nil);

global '(

      plotdriver!*         % modulename of the actual driver.

      plotmax!*            % maximal floating point number which
                           % gnuplot supports on the machine
                           % (mostly IEEE double or single precision).

      plotmin!*            % lower bound (=1/plotmax!*)

      variation!*          %  definition of y-bigstep for smooth

      plotoptions!*        % list for collecting the options.

);

fluid '(

      plotderiv!*          %  derivative for 2d plot

);

!#if(or (errorp (errorset '!*writingfaslfile nil nil)) 
        (not !*writingfaslfile) 
        (errorp (errorset '(load fcomp) nil nil)))
%  prin2t "*** No support for fast float!";
   symbolic macro procedure fdeclare u; nil;
   symbolic macro procedure thefloat u; cadr u;
!#endif

% Create .. as infix operator.

newtok '((!. !.) !*interval!*);

put('!*interval!*,'prtch,'! !.!.! );

if null get('!*interval!*,'simpfn)
  then <<precedence .., or; algebraic operator ..>>;

 % Reestablished these routines in order to support singularity handling
 % (which was better in some respects in Reduce 3.5) %WN

symbolic procedure ploteval3xysingular(ff,f,x,xx,dx,y,yy,dy,zhi,zlo);
 % set up an iteration approaching a critical point.
   <<dx:=dx/4; dy:=dy/4;
     ploteval3xysingular1(ff,f,x,xx,dx,y,yy,dy,zhi,zlo,
       plotevalform(ff,f,{x . (xx+dx), y . (yy+dy)}),0)
    >>;

symbolic procedure ploteval3xysingular1(ff,f,x,xx,dx,y,yy,dy,zhi,zlo,w,c);
  if null w then nil else if c>8 then nil else
  if w>zhi then zhi else
  if w<zlo then zlo else
  begin scalar wnew;
    dx:=dx/2; dy:=dy/2;
    wnew := plotevalform(ff,f,{x . (xx+dx), y . (yy+dy)});
    return
     if null wnew then nil else
     if abs(wnew-w) <abs wnew/20 then wnew else
       ploteval3xysingular1(ff,f,x,xx,dx,y,yy,dy,zhi,zlo,wnew,c+1);
  end;


% I need the following definition only at compile time.
macro procedure plotdriver u;
  {'apply,{'get,'plotdriver!*,mkquote cadr u},'list . cddr u};


endmodule;

end;