From: SourceForge.net <noreply@so...>  20060731 05:00:10

Bugs item #1054472, was opened at 20041026 03:35 Message generated for change (Comment added) made by robert_dodier You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1054472&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 Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: defint(log(1+exp(A+B*cos(phi))),phi,0,%pi) wrong Initial Comment: Maxima 5.9.0 C1) assume(B>0,BA>0)$ (C2) integrate(log(1+exp(A+B*cos(phi))),phi,0,%pi);  B B A (D2) 3 %PI LOG(%E (%E + %E )) But if we give A and B numerical values (C3) B:3$ A:2$ ev(D2,numer); (C4) (C5) (D5) 2.952421848475173 (C6) B:3.2$ A:3$ ev(D2,numer); (C7) (C8) (D8) .0191075509605848 while by evaluating the integral numerically we obtain something different (C11) B:3$ A:2$ romberg(log(1+exp(A+B*cos(phi))),phi,0,%pi); (C12) (C13) (D13) 7.506856487627962 (C14) B:3.2$ A:3$ romberg(log(1+exp(A+B*cos(phi))),phi,0,%pi); (C15) (C16) (D16) 0.663669430006855 The integrand does not look like the kind of thing that would give the romberg procedure any trouble (C25) plot2d(log(1+exp(A+B*cos(phi))),[phi,0,%pi])$ In fact, by visual inspection of the plot it is clear that the area under the curve is much closer to 0.66 (romberg's result) than to 0.02 (as integrate would have us believe). The same problem occurs if we use defint instead of integrate. Cheers.  >Comment By: Robert Dodier (robert_dodier) Date: 20060730 23:00 Message: Logged In: YES user_id=501686 Observed in 5.9.3cvs. Not sure, but it looks like integrate yields a different result when A and B are symbols compared to when they are given specific values A=2, B=3.  You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=104933&aid=1054472&group_id=4933 