[Maxima-bugs] [ maxima-Bugs-932076 ] ode2( 'diff(y, x)=%i*y+sin(x), y, x) => div by 0

 [Maxima-bugs] [ maxima-Bugs-932076 ] ode2( 'diff(y, x)=%i*y+sin(x), y, x) => div by 0 From: SourceForge.net - 2009-06-28 20:05:10 ```Bugs item #932076, was opened at 2004-04-09 01:06 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=932076&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core Group: None >Status: Closed >Resolution: Fixed Priority: 5 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: ode2( 'diff(y,x)=%i*y+sin(x), y, x) => div by 0 Initial Comment: ode2( 'diff(y,x)=%i*y+sin(x), y, x) gives division by 0 ---------------------------------------------------------------------- >Comment By: Dieter Kaiser (crategus) Date: 2009-06-28 22:05 Message: With the current CVS version 5.18post this differential equation gives a correct result: (%i53) ode2('diff(y,x)-%i*y-sin(x),y,x); (%o53) y = (%c-%i*(x-%i*%e^-(2*%i*x)/2)/2)*%e^(%i*x) (%i54) expand(%); (%o54) y = -%i*x*%e^(%i*x)/2+%c*%e^(%i*x)-%e^-(%i*x)/4 I think this is now correct because of an improvement of the routine SCE-INT in sin.lisp with revision 1.48. Closing this bug report as fixed. Dieter Kaiser ---------------------------------------------------------------------- Comment By: Robert Dodier (robert_dodier) Date: 2006-07-29 08:07 Message: Logged In: YES user_id=501686 Observed in 5.9.3cvs. ---------------------------------------------------------------------- Comment By: Stavros Macrakis (macrakis) Date: 2004-04-20 01:25 Message: Logged In: YES user_id=588346 Same problem if you solve the equation 'diff(y,x)= k*y+sin(x) -- the solution is not valid at k=%i, but it doesn't ask. Correct solution for k=%i is y = -((-x-%i*%c-%i)*sin(x)+(%i*x-%c)*cos(x))/2 ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=932076&group_id=4933 ```

 [Maxima-bugs] [ maxima-Bugs-932076 ] ode2( 'diff(y, x)=%i*y+sin(x), y, x) => div by 0 From: SourceForge.net - 2006-07-29 06:07:29 ```Bugs item #932076, was opened at 2004-04-08 17:06 Message generated for change (Comment added) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=932076&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. >Category: Lisp Core Group: None Status: Open Resolution: None Priority: 5 Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: ode2( 'diff(y,x)=%i*y+sin(x), y, x) => div by 0 Initial Comment: ode2( 'diff(y,x)=%i*y+sin(x), y, x) gives division by 0 ---------------------------------------------------------------------- >Comment By: Robert Dodier (robert_dodier) Date: 2006-07-29 00:07 Message: Logged In: YES user_id=501686 Observed in 5.9.3cvs. ---------------------------------------------------------------------- Comment By: Stavros Macrakis (macrakis) Date: 2004-04-19 17:25 Message: Logged In: YES user_id=588346 Same problem if you solve the equation 'diff(y,x)= k*y+sin(x) -- the solution is not valid at k=%i, but it doesn't ask. Correct solution for k=%i is y = -((-x-%i*%c-%i)*sin(x)+(%i*x-%c)*cos(x))/2 ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=932076&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-932076 ] ode2( 'diff(y, x)=%i*y+sin(x), y, x) => div by 0 From: SourceForge.net - 2009-06-28 20:05:10 ```Bugs item #932076, was opened at 2004-04-09 01:06 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=932076&group_id=4933 Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Lisp Core Group: None >Status: Closed >Resolution: Fixed Priority: 5 Private: No Submitted By: Stavros Macrakis (macrakis) Assigned to: Nobody/Anonymous (nobody) Summary: ode2( 'diff(y,x)=%i*y+sin(x), y, x) => div by 0 Initial Comment: ode2( 'diff(y,x)=%i*y+sin(x), y, x) gives division by 0 ---------------------------------------------------------------------- >Comment By: Dieter Kaiser (crategus) Date: 2009-06-28 22:05 Message: With the current CVS version 5.18post this differential equation gives a correct result: (%i53) ode2('diff(y,x)-%i*y-sin(x),y,x); (%o53) y = (%c-%i*(x-%i*%e^-(2*%i*x)/2)/2)*%e^(%i*x) (%i54) expand(%); (%o54) y = -%i*x*%e^(%i*x)/2+%c*%e^(%i*x)-%e^-(%i*x)/4 I think this is now correct because of an improvement of the routine SCE-INT in sin.lisp with revision 1.48. Closing this bug report as fixed. Dieter Kaiser ---------------------------------------------------------------------- Comment By: Robert Dodier (robert_dodier) Date: 2006-07-29 08:07 Message: Logged In: YES user_id=501686 Observed in 5.9.3cvs. ---------------------------------------------------------------------- Comment By: Stavros Macrakis (macrakis) Date: 2004-04-20 01:25 Message: Logged In: YES user_id=588346 Same problem if you solve the equation 'diff(y,x)= k*y+sin(x) -- the solution is not valid at k=%i, but it doesn't ask. Correct solution for k=%i is y = -((-x-%i*%c-%i)*sin(x)+(%i*x-%c)*cos(x))/2 ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=932076&group_id=4933 ```