@@ -1,71 +1,71 @@ - - SOFIA LAPLACE AND INVERSE LAPLACE TRANSFORM PACKAGE - - C. Kazasov, M. Spiridonova, V. Tomov - - -Reference: Christomir Kazasov, Laplace Transformations in REDUCE 3, Proc. - Eurocal '87, Lecture Notes in Comp. Sci., Springer-Verlag - (1987) 132-133. - -Some hints on how to use to use this package: - -Syntax: - - LAPLACE(,,) - - INVLAP(,,) - -where is the expression to be transformed, is the source -variable (in most cases depends explicitly of this variable) and - is the target variable. If is omitted, the package uses -an internal variable lp!& or il!&, respectively. - -The following switches can be used to control the transformations: - -lmon: If on, sin, cos, sinh and cosh are converted by LAPLACE into - exponentials, - -lhyp: If on, expressions e**(~x) are converted by INVLAP into hyperbolic - functions sinh and cosh, - -ltrig: If on, expressions e**(~x) are converted by INVLAP into - trigonometric functions sin and cos. - -The system can be extended by adding Laplace transformation rules for -single functions by rules or rule sets. In such a rule the source -variable MUST be free, the target variable MUST be il!& for LAPLACE and -lp!& for INVLAP and the third parameter should be omitted. Also rules for -transforming derivatives are entered in such a form. - -Examples: - - let {laplace(log(~x),x) => -log(gam * il!&)/il!&, - invlap(log(gam * ~x)/x,x) => -log(lp!&)}; - - operator f; - let{ - laplace(df(f(~x),x),x) => il!&*laplace(f(x),x) - sub(x=0,f(x)), - - laplace(df(f(~x),x,~n),x) => il!&**n*laplace(f(x),x) - - for i:=n-1 step -1 until 0 sum - sub(x=0, df(f(x),x,n-1-i)) * il!&**i - when fixp n, - - laplace(f(~x),x) = f(il!&) - }; - -Remarks about some functions: - -The DELTA and GAMMA functions are known. - -ONE is the name of the unit step function. - -INTL is a parametrized integral function - - intl(,,0,) - - which means "Integral of wrt taken from 0 to ", -e.g. intl(2*y**2,y,0,x) which is formally a function in x. - -We recommend reading the file LAPLACE.TST for a further introduction. + + SOFIA LAPLACE AND INVERSE LAPLACE TRANSFORM PACKAGE + + C. Kazasov, M. Spiridonova, V. Tomov + + +Reference: Christomir Kazasov, Laplace Transformations in REDUCE 3, Proc. + Eurocal '87, Lecture Notes in Comp. Sci., Springer-Verlag + (1987) 132-133. + +Some hints on how to use to use this package: + +Syntax: + + LAPLACE(,,) + + INVLAP(,,) + +where is the expression to be transformed, is the source +variable (in most cases depends explicitly of this variable) and + is the target variable. If is omitted, the package uses +an internal variable lp!& or il!&, respectively. + +The following switches can be used to control the transformations: + +lmon: If on, sin, cos, sinh and cosh are converted by LAPLACE into + exponentials, + +lhyp: If on, expressions e**(~x) are converted by INVLAP into hyperbolic + functions sinh and cosh, + +ltrig: If on, expressions e**(~x) are converted by INVLAP into + trigonometric functions sin and cos. + +The system can be extended by adding Laplace transformation rules for +single functions by rules or rule sets. In such a rule the source +variable MUST be free, the target variable MUST be il!& for LAPLACE and +lp!& for INVLAP and the third parameter should be omitted. Also rules for +transforming derivatives are entered in such a form. + +Examples: + + let {laplace(log(~x),x) => -log(gam * il!&)/il!&, + invlap(log(gam * ~x)/x,x) => -log(lp!&)}; + + operator f; + let{ + laplace(df(f(~x),x),x) => il!&*laplace(f(x),x) - sub(x=0,f(x)), + + laplace(df(f(~x),x,~n),x) => il!&**n*laplace(f(x),x) - + for i:=n-1 step -1 until 0 sum + sub(x=0, df(f(x),x,n-1-i)) * il!&**i + when fixp n, + + laplace(f(~x),x) = f(il!&) + }; + +Remarks about some functions: + +The DELTA and GAMMA functions are known. + +ONE is the name of the unit step function. + +INTL is a parametrized integral function + + intl(,,0,) + + which means "Integral of wrt taken from 0 to ", +e.g. intl(2*y**2,y,0,x) which is formally a function in x. + +We recommend reading the file LAPLACE.TST for a further introduction.