Yeah, the most recent version is 0.6.7! I recommend that you upgrade. :) Aaron Meurer On Mar 31, 2010, at 9:52 AM, Colin wrote:
> Great, thanks for this. This is probably implemented in a more recent > version of SymPy than 0.5.15? It's probably time I upgraded my Ubuntu > distribution... > > all the best > --Colin > > On 31 Mar, 16:30, "Aaron S. Meurer" <[email protected]> wrote: >> Use expr.rewrite(cos), as in >> >> In [22]: print a.rewrite(cos) >> 3**(1/2)*(I*sin(k_1/4) + cos(k_1/4))/45 + 3**(1/2)*(-I*sin(k_1/4) + >> cos(k_1/4))/45 + 3**(1/2)*(-I*sin(I*(I*k_1/4 - I*k_2*3**(1/2)/4)) + >> cos(I*(I*k_1/4 - I*k_2*3**(1/2)/4)))/45 + 3**(1/2)*(-I*sin(I*(-I*k_1/4 + >> I*k_2*3**(1/2)/4)) + cos(I*(-I*k_1/4 + I*k_2*3**(1/2)/4)))/45 + >> 3**(1/2)*(-I*sin(I*(I*k_1/8 + I*k_2*3**(1/2)/8)) + cos(I*(I*k_1/8 + >> I*k_2*3**(1/2)/8)))/45 + 3**(1/2)*(I*sin(-I*(-I*k_1/8 - I*k_2*3**(1/2)/8)) + >> cos(-I*(-I*k_1/8 - I*k_2*3**(1/2)/8)))/45 >> >> You could then use expand() to simplify things. >> >> Aaron Meurer >> On Mar 31, 2010, at 9:18 AM, Colin wrote: >> >>> Dear list, >>> I have expressions coming from my calculation of the type: >> >>> (1/45)*3**(1/2)*exp(-1/4*I*k_1 + (1/4)*I*k_2*3**(1/2)) + >>> (1/45)*3**(1/2)*exp(-1/8*I*k_1 - 1/8*I*k_2*3**(1/2)) + >>> (1/45)*3**(1/2)*exp((1/4)*I*k_1 - 1/4*I*k_2*3**(1/2)) + >>> (1/45)*3**(1/2)*exp((1/8)*I*k_1 + (1/8)*I*k_2*3**(1/2)) + >>> (1/45)*3**(1/2)*exp(-1/4*I*k_1) + (1/45)*3**(1/2)*exp((1/4)*I*k_1) >> >>> where k_1,k_2 are real numbers. What is the best way to automatically >>> rewrite this as a weighted sum of cosines? >> >>> all the best >>> --Colin >> >>> -- >>> 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]. >>> For more options, visit this group >>> athttp://groups.google.com/group/sympy?hl=en. >> >> > > -- > 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]. > For more options, visit this group at > http://groups.google.com/group/sympy?hl=en. > -- 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]. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
