Vinzent Steinberg wrote: > 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 > > > > If you modify trigsimp here is another problem. For this code:
from sympy import * x = Symbol('x') y = Symbol('y') e = cos(x)*tan(x) print e print trigsimp(e) The result is: cos(x)*tan(x) cos(x)*tan(x) Maybe there should be an option in trigsimp "not" to replace sin(x)/cos(x) with tan(x) and cos(x)/sin(x) with cot(x) ? *Actually the option should be to replace tan(x) with sin(x)/cos(x) and cot(x) with cos(x)/sin(x) before simplifying.* --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sympy-patches" group. To post to this group, send email to sympy-patches@googlegroups.com To unsubscribe from this group, send email to sympy-patches+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sympy-patches?hl=en -~----------~----~----~----~------~----~------~--~---