Aaron, thanks, that's definitely the right idea, but doesn't work, probably because of simplification. Here's an example:
What I really want is a k3/k1 term in the denominator that can be substituted. Any way to achieve this? On Thursday, November 10, 2016 at 3:54:30 PM UTC-5, Aaron Meurer wrote: > > SymPy expressions are immutable. You have to create a new expression. > I would recommend something like > > def mul_and_div_factor(expr, factor): > n, d = expr.as_numer_denom() > return (n*factor)/(d*factor) > > Aaron Meurer > > On Thu, Nov 10, 2016 at 7:40 AM, Scott Calabrese Barton > <[email protected] <javascript:>> wrote: > > Hi, I wonder if there is an easy way to multiply the numerator and > > denominator of a rational expression by the same factor. I'd like to do > this > > to group terms so that I can make a substitution. > > > > I tried making a function to do this: > > > > def tb(exp,factor): > > if exp.func==Mul and exp.args[-1].func==Pow \ > > and exp.args[-1].args[-1]==-1: > > e=exp*factor > > denom=e.args[-1].args[0] * factor > > e.args[-1].args[0] = denom > > > > return e > > > > > > > > Unfortunately it doesn't work because of immutable tuples. > > > > > > -- > > 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] <javascript:>. > > To post to this group, send email to [email protected] > <javascript:>. > > Visit this group at https://groups.google.com/group/sympy. > > To view this discussion on the web visit > > > https://groups.google.com/d/msgid/sympy/773995c5-ed93-42cd-a480-2e59bb9f4974%40googlegroups.com. > > > > For more options, visit https://groups.google.com/d/optout. > -- 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 https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/0a39376d-d426-4489-9ac2-656f68390844%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
