On Mar 27, 4:55 pm, Ondrej Certik <ond...@certik.cz> wrote:
> On Fri, Mar 27, 2009 at 8:34 AM, Vinzent Steinberg
>
> <vinzent.steinb...@googlemail.com> wrote:
>
> > This is strange, because just constructing such an expression triggers
> > this trivial simplification:
>
> >>>> (cos(x)**3)**(2/3)*cos(y)**2 - (cos(x)**3)**(5/3)*cos(y)**2 + \
> > ... 3*cos(x)**3*cos(y)**2 + cos(x)**2*cos(y)**2*tan(x)**2 + \
> > ... cos(x)**5*cos(y)**2*tan(x)**4
> > cos(y)**2 + 2*cos(x)**3*cos(y)**2 + cos(x)**2*cos(y)**2*tan(x)**2 + cos
> > (x)**5*cos(y)**2*tan(x)**4
>
> What is strange on this?
>
> O.
That it doesn't simplify for Alan:
Alan Bromborsky wrote:
> Here is a trigsimp problem, although the problem is not really in trigsimp.
> Run this code:
> from sympy import *
> x = Symbol('x')
> y = Symbol('y')
> s = sin(x)
> c = cos(x)
> S = sin(y)
> C = cos(y)
> e = (1-S**2)*(1+c)*(s**2+c**2)+C**2*(1-s**2)*c**3+C**2*(1-c**2)*c**3
> e = expand(e)
> print e
> print trigsimp(e,deep=True,recursive=True)
> and get:
> sin(x)**2*cos(x) - sin(x)**2*sin(y)**2*cos(x) + cos(x)**2 + sin(x)**2 -
> cos(x)**2*sin(y)**2 -
> cos(x)**3*sin(y)**2 - cos(x)**5*cos(y)**2 - sin(x)**2*sin(y)**2 +
> 2*cos(x)**3*cos(y)**2 -
> cos(x)**3*cos(y)**2*sin(x)**2 + cos(x)**3
> (cos(x)**3)**(2/3)*cos(y)**2 - (cos(x)**3)**(5/3)*cos(y)**2 +
> 3*cos(x)**3*cos(y)**2 +
> cos(x)**2*cos(y)**2*tan(x)**2 + cos(x)**5*cos(y)**2*tan(x)**4
> The problem is expressions of the form: (cos(x)**3)**(5/3)
> which probably prevent trigsimp from further simplification. Is their
> any simple way to insure3
> that (cos(x)**3)**(5/3) would be replaced by cos(x)**5!
Vinzent
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