Comment #11 on issue 1562 by asmeurer: Have trigsimp apply factor and
Poly.cancel() to sin's and cos's
http://code.google.com/p/sympy/issues/detail?id=1562
The symbol substation is no longer necessary in the new polys, but that is
about it:
In [15]: trigsimp(factor(simplify(a)))
Out[15]: -4
In [16]: trigsimp(a)
Out[16]:
< unsimplified expression >
so the fix should be as simple now as adding factor(simplify(expr)) or
something like that to the top of trigsimp().
But at least the wronskian comes out simpler:
In [17]: wronskian([x*sin(x), sin(x), 1, x*cos(x), cos(x)], x)
Out[17]:
2 2 4 4
- 8⋅cos (x)⋅sin (x) - 4⋅cos (x) - 4⋅sin (x)
so solve should be able to simplify it with just factor() and trigsimp()
(for the integrals with variation of parameters). It isn't
yet though:
In [20]: dsolve(f(x).diff(x, 5) + 2*f(x).diff(x, 3) + f(x).diff(x) - 1,
f(x), 'nth_linear_constant_coeff_variation_of_parameters')
<hangs>
I'd rather just have trigsimp() just work though.
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