Re: Simplifying trigonometric functions
- To: mathgroup at smc.vnet.net
- Subject: [mg94675] Re: [mg94662] Simplifying trigonometric functions
- From: "David Park" <djmpark at comcast.net>
- Date: Sat, 20 Dec 2008 06:19:35 -0500 (EST)
- References: <28161976.1229689867901.JavaMail.root@m02>
Here are two methods. The first is to Map TrigReduce directly to the y factors. Cos[x] Cos[y]^2 + Sin[y]^2; MapAt[TrigReduce, %, {{1, 2}, {2}}] The second method is to use a rule that operates only on the y factors. Cos[x] Cos[y]^2 + Sin[y]^2; % /. (f : (Sin | Cos))[y]^2 :> TrigReduce[f[y]^2] David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ From: Tang [mailto:tangwt at msn.com] Hi, I'm new to Mathematica. How can I define a rule to reduce the following expression from Cos[x] Cos[y]^2 + Sin[y]^2 to operate only on expressions involving y to Cos[x](1+Cos[2y])/2 + (1-Cos[2y])/2 Thanks for the help!