Aaron, Thanks so much. I ended up needing both techiniques to simplify the larger expression I was after; for now, using SymPy 0.7.2 is enough. I'll definitely try to the git version if needed!
On Wed, Jan 23, 2013 at 8:10 PM, Aaron Meurer <[email protected]> wrote: > trigsimp() would be what would do it, if anything. > > Some recent changes (after the last release) have improved trigsimp, > so that it can now do this. As a work-around, you can just factor it > first > > In [11]: print trigsimp(factor(expr2)) > 1 > > Another trick that works well is to replace sin(x)**2 with 1 - cos(x)**2: > > In [15]: expr2.subs(sin(s)**2, 1 - cos(s)**2).expand() > Out[15]: 1 > > Or you could try the git master trigsimp, which is much more powerful > than the one in the release. See > https://github.com/sympy/sympy/wiki/Getting-the-bleeding-edge. > > Aaron Meurer > > On Wed, Jan 23, 2013 at 2:10 PM, Bryan Jones <[email protected]> wrote: > > All, > > > > I'd like SymPy to simplify some trig expressions (see below), but I'm > > stumped. What's the appropriate call (I assume to one of the functions in > > http://docs.sympy.org/0.7.2/modules/simplify/simplify.html)? I've tried > > several and can't seem to figure out the right approach. > > > > > > from sympy import symbols, sin, cos > > > > from sympy.simplify import * > > > > s = symbols('s') > > > > expr = sin(s)**2 + cos(s)**2 > > > > print('Original expression: %s' % expr) > > > > print('Simplifies to: %s' % simplify(expr)) > > > > expr2 = (expr**2).expand() > > > > print('Original squared: %s' % expr2) > > > > print('Simplifies to: %s' % trigsimp(expr2)) > > > > > > The output: > > > > Original expression: sin(s)**2 + cos(s)**2 > > > > Simplifies to: 1 > > > > Original squared: sin(s)**4 + 2*sin(s)**2*cos(s)**2 + cos(s)**4 > > > > Simplifies to: sin(s)**4 - cos(s)**4 + 2*cos(s)**2 > > > > > > I'd like the last line to read: "Simplifies to: 1" > > > > Any ideas? > > > > Thanks! > > > > Bryan > > > > -- > > You received this message because you are subscribed to the Google Groups > > "sympy" group. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > > [email protected]. > > Visit this group at http://groups.google.com/group/sympy?hl=en. > > For more options, visit https://groups.google.com/groups/opt_out. > > > > > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > Visit this group at http://groups.google.com/group/sympy?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- Bryan A. Jones, Ph.D. Associate Professor Department of Electrical and Computer Engineering 231 Simrall / PO Box 9571 Mississippi State University Mississippi state, MS 39762 http://www.ece.msstate.edu/~bjones bjones AT ece DOT msstate DOT edu voice 662-325-3149 fax 662-325-2298 Our Master, Jesus Christ, is on his way. He'll show up right on time, his arrival guaranteed by the Blessed and Undisputed Ruler, High King, High God. - 1 Tim. 6:14b-15 (The Message) -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
