It would be nice if users didn't have to know about all of the little functions in sympy but could instead just state an objective function.
We often get the questions "I want my result in this form..." We often give the answers "try this function, then this one, then one of these two, whichever works best" This works but it requires human/listhost intervention. It would be nice if sympy could do this itself. In Fu simplification and in a few other functions it sort of can. Note that this would make a great GSoC project if anyone is interested. On Tue, Feb 18, 2014 at 3:56 AM, mario <[email protected]> wrote: > In fu.py there are several functions to manipulate trigonometric > expressions; in your example you > can use TR8 to expand products of sin-cos to sums; > > ``` > from sympy.simplify.fu import TR8 > from sympy.simplify.simplify import _mexpand > P = (D + F*sin(x) + G*cos(x) + H*sin(2*x) + J*cos(2*x))**2 > r = _mexpand(TR8(_mexpand(P))) > ``` > what is missing is the collection of the coefficients; it is easy to write > a function collecting terms, > but I suspect that there is already a simple way in SymPy to do this. > > > > > On Friday, February 7, 2014 8:28:20 AM UTC+1, Alex Clifton wrote: >> >> I was wondering if there was a way to "guide" sympy in performing trig >> identities to get the output into a specific form? Below, I go into detail >> and have attached a working version of the file for reference. >> >> In the expression of P, the coefficients D, F, G, H, and J are assumed to >> be real valued. I have left some commented print statements to show the >> different simplify options I have tried. I have performed this calculation >> by hand and I know there are several trig substitutions that need to be >> made in order to get the final expression in the form that I would like. >> That form is to get rid of all powers of trig functions greater than 1 by >> appropriate substitutions. Of course, I cannot expect sympy to know that I >> want things in this form so I am not surprised when the different simplify >> statements do not give me that form. I was wondering what would be the >> best way to guide sympy in order to get the final output of P to be in the >> following form: >> >> K + Lsin(x) + Mcos(x) + Nsin(2x) + Qcos(2x) + Rsin(3x) + Scos(3x) + >> Tsin(4x) + Vcos(4x) >> >> Where K, L, M, N, Q, R, S, T, and V are now combinations of the original >> D, F, G, H, and J. >> >> By the way, I am not as concerned now about the coefficients as I am >> getting rid of the higher powers of the trig functions. Although if people >> would like to weigh in on that, that would be great. If more detail is >> needed, please let me know and I'd be happy to provide it. >> >> -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sympy. > 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 unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out.
