Unfortunately, unless I am mistaken, there isn't a function to do exactly what you want yet. We probably should make one.
I was able to get pretty close using Add(*[(factor(Add(*i))) for i in sift(Add.make_args(num), lambda i: Poly(i, log(R), log(R_1)).total_degree()).values()]) Basically, I split out each term by its degree in terms of log(R) and log(R_1), and then factored those terms independently. This works in this case because all the log terms are of the form (log(R) - log(R_1))**n for some n, so to get the terms corresponding to the factor for each n, one just needs to gather all the terms where the total degree in log(R) and log(R_1) equals n. As for combining the logs at that point, logcombine works, but it goes a little too far. We should add some flags to it to allow disabling combining of exponents. You can get what you want using subs(log(R) - log(R_1), log(R/R_1)), though, since all the logs are of that form. More generally you could use replace with a wild symbol. Aaron Meurer On Thu, Aug 15, 2013 at 11:09 AM, Boris Kheyfets <[email protected]> wrote: > Oh, no problem: > > Gamma_R**2*R**4*R_1**2 + 4*Gamma_R**2*R**2*R_1**4*log(R)**3 - > 12*Gamma_R**2*R**2*R_1**4*log(R)**2*log(R_1) - > 8*Gamma_R**2*R**2*R_1**4*log(R)**2 + > 12*Gamma_R**2*R**2*R_1**4*log(R)*log(R_1)**2 + > 16*Gamma_R**2*R**2*R_1**4*log(R)*log(R_1) + 2*Gamma_R**2*R**2*R_1**4*log(R) > - 4*Gamma_R**2*R**2*R_1**4*log(R_1)**3 - > 8*Gamma_R**2*R**2*R_1**4*log(R_1)**2 - 2*Gamma_R**2*R**2*R_1**4*log(R_1) - > Gamma_R**2*R**2*R_1**4 - 2*Gamma_R**2*R_1**6*log(R)**2 + > 4*Gamma_R**2*R_1**6*log(R)*log(R_1) - 2*Gamma_R**2*R_1**6*log(R_1)**2 + > 4*Gamma_R*P*R**4*R_1**2*log(R) - 4*Gamma_R*P*R**4*R_1**2*log(R_1) + > 2*Gamma_R*P*R**4*R_1**2 - 8*Gamma_R*P*R**2*R_1**4*log(R)**3 + > 24*Gamma_R*P*R**2*R_1**4*log(R)**2*log(R_1) - > 8*Gamma_R*P*R**2*R_1**4*log(R)**2 - > 24*Gamma_R*P*R**2*R_1**4*log(R)*log(R_1)**2 + > 16*Gamma_R*P*R**2*R_1**4*log(R)*log(R_1) + > 8*Gamma_R*P*R**2*R_1**4*log(R_1)**3 - 8*Gamma_R*P*R**2*R_1**4*log(R_1)**2 - > 2*Gamma_R*P*R**2*R_1**4 + 4*Gamma_R*P*R**2*R_1**2*log(R)**2 - > 8*Gamma_R*P*R**2*R_1**2*log(R)*log(R_1) - 4*Gamma_R*P*R**2*R_1**2*log(R) + > 4*Gamma_R*P*R**2*R_1**2*log(R_1)**2 + 4*Gamma_R*P*R**2*R_1**2*log(R_1) - > 4*Gamma_R*P*R_1**4*log(R) + 4*Gamma_R*P*R_1**4*log(R_1) + > 8*P**2*R**4*R_1**2*log(R)**2 - 16*P**2*R**4*R_1**2*log(R)*log(R_1) + > 8*P**2*R**4*R_1**2*log(R_1)**2 + 2*P**2*R**4*R_1**2 - 2*P**2*R**2*R_1**4 - > 8*P**2*R**2*R_1**2*log(R)**2 + 16*P**2*R**2*R_1**2*log(R)*log(R_1) - > 8*P**2*R**2*R_1**2*log(R) - 8*P**2*R**2*R_1**2*log(R_1)**2 + > 8*P**2*R**2*R_1**2*log(R_1) + 2*P**2*R**2 - 2*P**2*R_1**2 > > I need to combine logs. > > Here's a py code, just in case: > > #!/usr/bin/python2.7 > # -*- coding:utf-8 -*- > > # ========= > ## imports: > > from __future__ import division > > from sympy import * > init_printing(pretty_print=True, use_unicode=True, wrap_line=False, > no_global=True) > > > # ====== > ## init: > > # real vars: > > var(""" > gamma_rr gamma_ff gamma_sum Gamma_R > g_l g_0 g__2 > """, real=True) > > # positive vars: > > var(""" > gamma gamma_R > r R_1 R_2 R > P > """, positive=True) > > > # =========== > ## functions: > > g_l = ( > (Gamma_R + 2 * P) > / > (2 * log(R/R_1)) > ) > > g_0 = ( > (Gamma_R * log(R/R_1) + P) > / > (2 * log(R/R_1)) > ) > > g_2 = ( > (R_1**2 * Gamma_R * log(R/R_1) + P) > / > (2 * log(R/R_1)) > ) > > gamma_ff = ( > g_l * ( log(r/R_1) + 1 ) > - g_0 > - g_2/r**2 > ) > > R_2 = R > > > intgrl = together(cancel(integrate(gamma_ff**2 * r, (r, R_1, R_2)))) > den = denom(intgrl) > num = numer(intgrl) > print str(num) > > > -- > 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.
