Possible to have rational times pi recognized as non-integer?
Subject: Possible to have rational times pi recognized as non-integer?
From: Karl-Dieter Crisman
Date: Tue, 20 Nov 2012 17:13:57 -0500
(%i5) display2d:false;
(%o5) false
(%i6) integrate(log(cot(x)-1),x,0,%pi/4);
Is %pi/8 an ?integer?
n;
Is %pi/4 an ?integer?
n;
Is 2*%pi an ?integer?
n;
(%o6) -(%i*(2*li[2](%i+1)-2*li[2](1-%i))+%pi*log(2))/4
+%i*li[2]((%i+1)/2)/2-%i*li[2](-(%i-1)/2)/2
I know that in general such checking is quite tricky and presumably
resource-intensive. Is it possible to write a rule so that during
such checks well-known irrationals times rationals are automatically
known not to be integers? If so, I'll be happy to file a bug report.