Factor inside argument

Question

How do you use Factor so that it will factor expressions inside the arguments of some bigger expression.

For example

 Factor[ Cos[t w - t z]]

gives

 Cos[t w - t z]

but i would like it to give:

 Cos[t(w - z)]

swish · Accepted Answer · 2013-02-03 00:40:32Z

up vote 1 down vote accepted

You need to Map it:

Map[Factor, Cos[t w - t z]]

Or with infix notation:

Factor /@ Cos[t w - t z]

answered Feb 3 at 0:40

swish
1,100115

	For more complicated expressions, `MapAll` may prove useful, working on all levels: compare `Factor //@ Cos[t w - t z + Sin[a x + a y]]` to `Factor /@ Cos[t w - t z + Sin[a x + a y]]` – VF1 Feb 3 at 0:57
	Thanks @VF1, that is the general question i was trying to address – AimForClarity Feb 5 at 2:17

RunnyKine · Answer 2 · 2013-02-03 00:35:25Z

up vote 1 down vote

You want to use Collect instead of Factor.

Cos[Collect[t w - t z, t]]

This gives:

Cos[t (w - z)]

Hope it helps.

answered Feb 3 at 0:35

RunnyKine
1,1721111

2 Answers