Re: Dividing top and bottom

• To: mathgroup at smc.vnet.net
• Subject: [mg15661] Re: Dividing top and bottom
• From: "Allan Hayes" <hay at haystack.demon.co.uk>
• Date: Sat, 30 Jan 1999 04:28:54 -0500 (EST)
• References: <786uft\$29u@smc.vnet.net> <78pb5e\$cto@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Nicolas B.E. Sawyer wrote in message <78pb5e\$cto at smc.vnet.net>...
>How can I divide the denominator and numerator of an expression by a
>chosen variable and stop the result from simplifying. For example, how
>do I  divide the top and bottom of b/(b-a) by b to give 1/(1-a/b).
>
>Thanks
>
>--
>Nicolas B.E. Sawyer
>
>
>Department of Electrical and Electronic Engineering, University of
>Nottingham,
>University Park,
>Nottingham,
>NG7 2RD.
>
>Tel: +44 115 9515151 ext 12028
>Fax: +44 115 9515616
>
>E-mail: nbes at eee.nottingham.ac.uk
>

Nicolas,

Get the simplification (or other transformation you may want) in first:

( b/(b-a) )/.(x_./y_ ):> Simplify[x/b]/ Simplify[y/b]

1/(1 - a/b)

The dot in x_. allows for

( 1/(b-a) )/.(x_./y_ ):> Simplify[x/b]/ Simplify[y/b]

1/((1 - a/b)*b)

OR

Simplify[Numerator[#]/b] /  Simplify[Denominator[#]/b]&[( b/(b-a) )]

1/(1 - a/b)

Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565

```

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