Re: Combining Fractions with Identical Denominator?

*To*: mathgroup at smc.vnet.net*Subject*: [mg81023] Re: [mg80994] Combining Fractions with Identical Denominator?*From*: Sseziwa Mukasa <mukasa at jeol.com>*Date*: Sat, 8 Sep 2007 03:51:38 -0400 (EDT)*References*: <200709070607.CAA06723@smc.vnet.net>

On Sep 7, 2007, at 2:07 AM, Jung-Tsung Shen wrote: > I have a sum of a series of fractions (symbolic) of about 50 terms. > How can I have Mathematica to sum up those with the same denominator? > By inspection, there are about 5 different denominators. I have wrote > a simple rule to compare the denominator term by term, but it's rather > slow. Moreover, sometimes the denominators differ only with a +/- > sign, a numerical factor (say, 1/2), or a complex i. > > In mathematical terms, I have a series in the following form (the > number of terms can vary): > > N1/D1 + N2/D2 + ... + N50/D50 > > These Di's form 5 different groups. Within each group, there are > proportional to each other. How could I sum up this series such that > those terms with Di in the same group is summed? Sort the terms according to the denominator group then split the lists and apply together to each sublist. Regards, Ssezi

**References**:**Combining Fractions with Identical Denominator?***From:*"Jung-Tsung Shen" <jushen@gmail.com>