I didn't try, but using a tellsimpafter, I think you can have
ilt try your code on failure. Do something like (maybe ilt
needs a
block([simp : false], tellsimpafter(ilt(f,s,t), ilap_1(f)));
Maybe your ilap_1 should have three arguments (as does ilt).
Thanks for your contribution.
Barton
-----maxima-bounces at math.utexas.edu wrote: -----
>To:?"maxima at math.utexas.edu"?<maxima at math.utexas.edu>
>From:?Sheldon?Newhouse?<sen1 at math.msu.edu>
>Sent?by:?maxima-bounces at math.utexas.edu
>Date:?03/13/2009?04:14PM
>Subject:?[Maxima]?More?on?enhanced?laplace?transforms
>
>Hello,
>?I?have?developed?a?very?primitive?extension?to?the?laplace?transform
>routines?to?deal?with?the?kinds?of?discontinuous?functions?often?taught
>in?basic?ODE?courses.
>
>The?direct?routine?(i.e.,?taking?the?Laplace?transform?using?some
>unit_step?functions)?is?a?simple?wrapper?around?the?'specint'?program?in
>maxima?(thanks?to?Dieter?Kaiser?for?alerting?me?about?this?routine?and
>its?use?in?Laplace?transforms).
>
>The?inverse?routine?is?a?pretty?sloppy?hack?and?only?seems?to?work?for
>linear?combinations?of?polynomials?and?unit_step?functions.
>
>Expressions?involving??direct?transforms?including?exponential?and?trig
>functions?are?just?too?complicated?for?the?present?version.??The
>transforms?have?to?be?massaged?first?to?get?rid?of?expressions?like
>exp(A*s)?in?the?denominators,?etc.
>
>To?save?writing,?the?direct?routine?is?called?'lap(f)'?where?f?is?a
>function?of?t,?and
>?the?inverse?routine?is?ilap(F)?where?F?is?a?function?of?s.
>
>Examples:
>(%i26)?f:?sum(unit_step(t-i)*(t+1)^i,i,1,3);
>
>(%o26)?(t+1)*ustep(t-1)+(t+1)^2*ustep(t-2)+(t+1)^3*ustep(t-3)
>(%i27)?lap(f);
>
>(%o27)
>%e^-(3*s)*((2*s^3+s^2)*%e^(2*s)+(9*s^3+6*s^2+2*s)*%e^s+64*s^3+48*s^2
>??????????????????????????????????????+24*s+6)
>????????/s^4
>(%i28)?ilap(%);
>
>(%o28)?(t-1)*ustep(t-1)+2*ustep(t-1)+(t-2)^2*ustep(t-2)+6*(t-2)*ustep(t-2)
>
>+9*ustep(t-2)+(t-3)^3*ustep(t-3)+12*(t-3)^2*ustep(t-3)
>???????????????????????+48*(t-3)*ustep(t-3)+64*ustep(t-3)
>(%i29)?expand(%o28?-%o26);
>
>(%o29)?0
>
>
>I?have?put?a?file?called?'My_laplace.mac"??on?the?web?at
>??http://janus.math.msu.edu/sen/WWW/Maxima_Laplace
>
>in?case?anyone?is?interested.??(Note:?this?is?new?and?probably?has
>bugs.??All?I?can?say?is?that?I?tested?it?with?problems?in?some?basic?ODE
>books?and?it?works?on?them).
>
>I?would?appreciate?any?comments?which?might?improve?the?code?and?make,
>perhaps,??a?useful?research?tool.
>
>-sen
>
>
>
>
>
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