RE: COLLECT and application of various commands to each coefficient
- To: mathgroup at smc.vnet.net
- Subject: [mg21247] RE: [mg21135] COLLECT and application of various commands to each coefficient
- From: "Ersek, Ted R" <ErsekTR at navair.navy.mil>
- Date: Mon, 20 Dec 1999 02:28:07 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Blimbaum Jerry wrote:
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I want to simplify a long expression using the Collect command. I
notice that it allows you to apply a command to each of the coefficients,
e.g.
Collect[expr,{Cos[x],Sin[x]},Simplify]
But Simplify here applies to both coefficients. What if I want to
do different things with each coefficient, e.g.
Collect[expr,{Cos[x],Sin[x]},{Collect coefficient of Cos[x] in terms
of x^2,Simplify Coefficients of Sin[x]]}]
Can this be done within the Collect command?
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REPLY:
The line below should help a lot.
Notice I use (lhs:>rhs) instead of (lhs->rhs).
If (lhs->rhs) is used any value assigned to (c1) is used in Simplify[c1].
For more on this subject down load the files at:
http://www.mathsource.com/cgi-bin/msitem?0210-609
In[12]:=
Collect[expr,{Cos[x],Sin[x]}]/.(c1_ Sin[x]:>Simplify[c1]Sin[x])
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Regards,
Ted Ersek
For Mathematica tips, tricks see
http://www.dot.net.au/~elisha/ersek/Tricks.html