## [Maxima-bugs] [ maxima-Bugs-887646 ] bogus PV integral [defint(exp(a*x), x, 0, inf)]

 [Maxima-bugs] [ maxima-Bugs-887646 ] bogus PV integral [defint(exp(a*x), x, 0, inf)] From: SourceForge.net - 2009-05-27 00:08:51 ```Bugs item #887646, was opened at 2004-01-30 15:49 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=887646&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 - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Barton Willis (willisbl) Assigned to: Nobody/Anonymous (nobody) Summary: bogus PV integral [defint(exp(a*x),x,0,inf)] Initial Comment: (C1) defint(exp(a*x),x,0,inf); Is a positive, negative, or zero? zero;Principal Value (D1) 0 This isn't a PV integral; the integral diverges when a == 0. (C2) build_info(); Maxima version: 5.9.0 Maxima build date: 19:10 2/9/2003 host type: i686-pc-mingw32 lisp-implementation-type: Kyoto Common Lisp lisp-implementation-version: GCL-2-5.0 ---------------------------------------------------------------------- >Comment By: Dieter Kaiser (crategus) Date: 2009-05-27 02:08 Message: The behavior has changed: The sign of a is unknown. Maxima returns a noun form: (%i3) defint(exp(a*x),x,0,inf); (%o3) 'integrate(%e^(a*x),x,0,inf) The sign of a is negative. We get the correct solution: (%i4) assume(a<0)\$ (%i5) defint(exp(a*x),x,0,inf); (%o5) -1/a The sign of the parameter b is positive. The integral is divergent: (%i6) assume(b>0)\$ (%i7) defint(exp(b*x),x,0,inf); defint: integral is divergent. -- an error. To debug this try debugmode(true); Up to here the solutions are correct and consistent. We assume a paramter less or equal zero and get a divergent result. I think, this should give a noun form too: (%i10) forget(a<0)\$ (%i11) assume(a<=0)\$ (%i12) defint(exp(b*x),x,0,inf); defint: integral is divergent. -- an error. To debug this try debugmode(true); This is again correct. The integral is divergent when b is greater or equal zero: (%i13) forget(b>0)\$ (%i14) assume(b>=0)\$ (%i15) defint(exp(b*x),x,0,inf); defint: integral is divergent. -- an error. To debug this try debugmode(true); Perhaps we can change the one open case for a parameter a<=0. Then all cases will be correct. Dieter Kaiser ---------------------------------------------------------------------- Comment By: Harald Geyer (hgeyer) Date: 2008-03-25 04:00 Message: Logged In: YES user_id=929336 Originator: NO Still observed in 5.14.0 and cvs HEAD from 2008-03-25 ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=887646&group_id=4933 ```

 [Maxima-bugs] [ maxima-Bugs-887646 ] bogus PV integral [defint(exp(a*x), x, 0, inf)] From: SourceForge.net - 2008-03-25 03:00:49 ```Bugs item #887646, was opened at 2004-01-30 15:49 Message generated for change (Comment added) made by hgeyer You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=887646&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 - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Barton Willis (willisbl) Assigned to: Nobody/Anonymous (nobody) Summary: bogus PV integral [defint(exp(a*x),x,0,inf)] Initial Comment: (C1) defint(exp(a*x),x,0,inf); Is a positive, negative, or zero? zero;Principal Value (D1) 0 This isn't a PV integral; the integral diverges when a == 0. (C2) build_info(); Maxima version: 5.9.0 Maxima build date: 19:10 2/9/2003 host type: i686-pc-mingw32 lisp-implementation-type: Kyoto Common Lisp lisp-implementation-version: GCL-2-5.0 ---------------------------------------------------------------------- >Comment By: Harald Geyer (hgeyer) Date: 2008-03-25 04:00 Message: Logged In: YES user_id=929336 Originator: NO Still observed in 5.14.0 and cvs HEAD from 2008-03-25 ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=887646&group_id=4933 ```
 [Maxima-bugs] [ maxima-Bugs-887646 ] bogus PV integral [defint(exp(a*x), x, 0, inf)] From: SourceForge.net - 2009-05-27 00:08:51 ```Bugs item #887646, was opened at 2004-01-30 15:49 Message generated for change (Comment added) made by crategus You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=887646&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 - Integration Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Barton Willis (willisbl) Assigned to: Nobody/Anonymous (nobody) Summary: bogus PV integral [defint(exp(a*x),x,0,inf)] Initial Comment: (C1) defint(exp(a*x),x,0,inf); Is a positive, negative, or zero? zero;Principal Value (D1) 0 This isn't a PV integral; the integral diverges when a == 0. (C2) build_info(); Maxima version: 5.9.0 Maxima build date: 19:10 2/9/2003 host type: i686-pc-mingw32 lisp-implementation-type: Kyoto Common Lisp lisp-implementation-version: GCL-2-5.0 ---------------------------------------------------------------------- >Comment By: Dieter Kaiser (crategus) Date: 2009-05-27 02:08 Message: The behavior has changed: The sign of a is unknown. Maxima returns a noun form: (%i3) defint(exp(a*x),x,0,inf); (%o3) 'integrate(%e^(a*x),x,0,inf) The sign of a is negative. We get the correct solution: (%i4) assume(a<0)\$ (%i5) defint(exp(a*x),x,0,inf); (%o5) -1/a The sign of the parameter b is positive. The integral is divergent: (%i6) assume(b>0)\$ (%i7) defint(exp(b*x),x,0,inf); defint: integral is divergent. -- an error. To debug this try debugmode(true); Up to here the solutions are correct and consistent. We assume a paramter less or equal zero and get a divergent result. I think, this should give a noun form too: (%i10) forget(a<0)\$ (%i11) assume(a<=0)\$ (%i12) defint(exp(b*x),x,0,inf); defint: integral is divergent. -- an error. To debug this try debugmode(true); This is again correct. The integral is divergent when b is greater or equal zero: (%i13) forget(b>0)\$ (%i14) assume(b>=0)\$ (%i15) defint(exp(b*x),x,0,inf); defint: integral is divergent. -- an error. To debug this try debugmode(true); Perhaps we can change the one open case for a parameter a<=0. Then all cases will be correct. Dieter Kaiser ---------------------------------------------------------------------- Comment By: Harald Geyer (hgeyer) Date: 2008-03-25 04:00 Message: Logged In: YES user_id=929336 Originator: NO Still observed in 5.14.0 and cvs HEAD from 2008-03-25 ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=887646&group_id=4933 ```