Interesting failure of Collect

*To*: mathgroup at smc.vnet.net*Subject*: [mg61307] Interesting failure of Collect*From*: "Blimbaum, Jerry CIV NSWC PC" <jerry.blimbaum at navy.mil>*Date*: Fri, 14 Oct 2005 22:22:38 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Given the expr = Sin[p]/(4 Pi a) + Sin[p]/(4 Pi b) and then applying the command Collect[expr, Sin[p]/(4 Pi)] works as it should, however, expr2 = Sin[p]/(4 Pi a) - Sin[p]/(4 Pi b) leaves the expression untouched. (I realize I could use Simplify but this problem occurred on a much longer expression and this is intended just to convey the basic idea)....for longer expressions the Collect process works for all quantities with a + sign but the one with a minus sign will not be collected.....strikes me as a "bug"..... thanks....jerry blimbaum

**Follow-Ups**:**Re: Interesting failure of Collect***From:*<bsyehuda@gmail.com>

**Re: Interesting failure of Collect***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>