Le 15/04/2011 02:39, Michael Orlitzky a écrit :
Am I going crazy?
sage: integrate(cos(2*x)*cos(x), x, 0, pi)
4/3
Actually Sage seems not to get the correct primitive :
----------------------------------------------------------------------
| Sage Version 4.6.1, Release Date: 2011-01-11 |
| Type notebook() for the GUI, and license() for information. |
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sage: f(x)=cos(2*x)*cos(x)
sage: F=f.integrate(x)
sage: F.diff(x).simplify_trig()
x |--> 2*sin(x)*cos(x)^2
Anyway, computation by hand shows that a primitive of cos(2x)cos(x) is
(-2/3)*sin(x)^3+sin(x)
The correct answer is thus zero and sage is wrong.
My two cents
Laurent
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