sympy

I have an expression which has both sines and cosines and would like to write it using only sines (or cosines), possibly using the power-reduction formula . I tried to use SymPy but I cannot make it to "rewrite" to the desired output: angle = symbols('angle') print (sin(angle)**2).rewrite(sin, cos) # (1 - cos(2*angle))/2 print ((1 - cos(2*angle))/2).rewrite(cos, sin) # sin(angle)**2 Is there any way to tell Sympy to rewrite such expression using only sines (or cosines)? unutbu The sympy.simplify.fu module defines a number of transformations based on trig identities: TR0 - simplify expression

I'd like to split a string like 3cm/µs² + 4e-4 sqmiles/km/h**2 into its SI unit (in this case, m/s**2 ) and its magnitude (in multiples of that unit). Since sympy provides both a parsing module and many physical units and SI prefixes , I guess using sympy would be a good idea. But what is a nice way to achieve this? I'd write an algorithm like the following, but I'd like to avoid reinventing a squared wheel: Treat the transition between a number and a letter (except for the 4e-4 like syntax) and whitespace (unless its next to an explicit operator) as multiplication, then tokenize Replace each

I'm writing my own Newton-Raphson algorithm in Python using sympy and numpy . The code is below but you can ignore this and skip on to the error: CODE def newtonRhapson(fncList, varz, x0): jacob = [] for fnc in fncList: vec = [] for var in varz: res = fnc.diff(var) for i in range(len(varz)): res = res.subs(varz[i], x0[i]) vec.append(res) jacob.append(numpy.array(vec, dtype='float64')) fx0=[] for fnc in fncList: res2 = fnc for i in range(len(varz)): res2 = res2.subs(varz[i], x0[i]) fx0.append(res2) j = jacob f = fx0 print j print '' print f print numpy.linalg.solve(j,f).tolist() The arguments

I cannot find a way to have SymPy expand products like cos(a)*cos(b) into sum of trig functions of sum of angles. from sympy import * init_printing() wrf,wlo,t = symbols('\omega_RF \omega_LO t') c = cos(wrf*t)*cos(wlo*t) expand_trig(c) Keeps the product intact. simplify(c) or trigsimp(c) also do not give any alternative form. I would like to have cos(a)*cos(b) to be expanded to 1/2*(cos(a+b) + cos(a-b)) ...any hints? unutbu Per the docstring, help(sympy.fu) , fu will try to minimize the objective function measure . By default this first minimizes the number of trig terms and then minimizes the

I have an expression as: 1/(x+1)+4*x/(x-1)+3-4*x**2+10*x**2 What I need is a list that contain the terms in this expression. i.e. [1/(x+1), 4*x/(x-1), 3, -4*x**2 , 10*x**2] update : It should not collect like terms. Therefore the list should have -4*x** 2 and 10*x** 2 separately and not 6*x**2 after collecting like terms. Based on the question and comments, if you can get the expression as a string, you can do something like this if you want to avoid term collection. (sympify("1/(x+1)+4*x/(x-1)+3-4*x**2+10*x**2", evaluate=False)).args this will return all the terms without collecting like

I'm trying to solve a set of equations with SymPy 0.7.1: from sympy import * equations = [ Eq(S('vf'), S('vi + a*t')), Eq(S('d'), S('vi*t + 1/2*a*t**2')), Eq(S('a'), S('10')), Eq(S('d'), S('60')), Eq(S('vi'), S('5')) ] print solve(equations) produces the correct result, but in a strange order: [(-4, 10, 60, -35, 5), (3, 10, 60, 35, 5)] How can I identify which value fits which variable? The variable order seems arbitrary. The documentation suggests providing additional arguments: print solve(equations, var('a'), var('d'), var('t'), var('vi'), var('vf')) But this seems to have no effect. Thanks

I'm using a dark background for ipython. I would like to have sympy expressions pretty-printed with LaTeX. Problem is the current LaTeX font is black. How can I change LaTeX font colors in the ipython terminal? asmeurer You can set the forecolor and backcolor options in sympy.init_printing . For example, to print the equations in blue, use In [1]: init_printing(forecolor="Blue") 来源： https://stackoverflow.com/questions/18257270/control-latex-expression-color-in-ipython-qtconsole