rtoy
commented
1 month ago Imported from SourceForge on 2024-07-08 13:57:52 Created by crategus on 2010-01-11 00:06:06 Original: https://sourceforge.net/p/maxima/bugs/1857/#733e
I think this integral should be divergent for all parameters a. Therefore we have two issues with this integeral:
For an arbitrary parameter a we get a noun form:
(%i1) integrate(x*cos(a*x),x,minf,inf); (%o1) 'integrate(x*cos(a*x),x,minf,inf)
For a positive parameter we get the result zero:
(%i2) assume(a>0)$
(%i3) integrate(x*cos(a*x),x,minf,inf); (%o3) 0 (%i4) integrate(x*cos(x),x,minf,inf); (%o4) 0
Now a negative parameter. Again a noun form:
(%i5) assume(b<0)$ (%i6) integrate(x*cos(b*x),x,minf,inf);
Because we have cos(-x) = cos(x) the sign should not change the result. I think all integrals should be divergent.
Dieter Kaiser
Imported from SourceForge on 2024-07-08 13:57:51 Created by *anonymous on 2009-12-22 15:24:55 Original: https://sourceforge.net/p/maxima/bugs/1857
I am finding the following possible regression from 5.19.1 to 5.20.0 (also in 5.20.1):
5.19.1 (%i1) integrate(x*cos(-y*x),x,minf,inf); (%o1) 0
5.20.0 (%i1) integrate(x*cos(-y*x),x,minf,inf); (%o1) <ascii art indicating the integral is returned as a nounform>
This is with SBCL and ECL.