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Re: Extract a part of expression

• To: mathgroup at smc.vnet.net
• Subject: [mg124373] Re: Extract a part of expression
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Tue, 17 Jan 2012 05:59:59 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <201201162207.RAA15301@smc.vnet.net>

expr = HoldForm[(x^2 Cos[x] (Sin[2 x] Tan[x]))/(E^x*x*Csc[x]^2)];

expr /. x_/y_ -> x // ReleaseHold

x^2*Sin[x]*Sin[2*x]

expr /. x_/y_ -> y // ReleaseHold

E^x*x*Csc[x]^2


Bob Hanlon

On Mon, Jan 16, 2012 at 5:07 PM, Miguel Gil <misvrne at gmail.com> wrote:
> How I can extract the full numerator (or denominator) of an expression of the form g (x) / w (x)?.
> I tried to do with Numerator [expr], but returns a wrong result. I tried with the attribute HoldForm [expr] and can not get the correct result.
>
> For example:
>  expr = (x ^ 2 Cos [x] (Sin [2x], Tan [x ]))/( E ^ x * x * Csc [x] ^ 2)
>

• References:
  • Extract a part of expression
    • From: Miguel Gil <misvrne@gmail.com>