conversion of sin to cos
- To: mathgroup at smc.vnet.net
- Subject: [mg87058] conversion of sin to cos
- From: glenn077 at gmail.com
- Date: Sun, 30 Mar 2008 01:18:07 -0500 (EST)
Hello all, Here is my problem. I have a very long product of cosines with arguments of the form k*Pi, k being integers. I want to convert this expression to a sum of cosines. TrigReduce works fine, except that it converts cos to sin. So, I want all the sin (after the TrigReduce) to be converted to cos and the arguments be of the form p*Pi, p being rational of course. It has something to do with Hold or HoldAll, but I don't know the details. Or perhaps the TrigReduce can be overridden somehow. Can someone help? Thank's for your time.