Re: Simply but handy question

• To: mathgroup at smc.vnet.net
• Subject: [mg124857] Re: Simply but handy question
• From: Alexei Boulbitch <Alexei.Boulbitch at iee.lu>
• Date: Thu, 9 Feb 2012 05:42:53 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```Dear group members,

I am new to mathematica (well, I'm not actually but I haven't used it

in 5 years +).

Is there an easy way to return a matrix X of 1's and 0's to test

whether the entries in Y

are different from zero.

i.e.,

if Y = {{a,b},{0,c}}

Then X would return

X = {{1,1},{0,1}}

This would be handy for very large or complicated matrices where one

would like to know if specific entries are zero?

Many thanks,

Paul

Hi, Paul,

Try this:

matrix1 = {{a, b}, {0, c}};

matrix2 = {{a, b, 0}, {c, 0, 15}, {0, 2, d}};

g[a_] := If[a =!= 0, 1, 0];

Map[g, matrix1, {2}] // MatrixForm

Map[g, matrix2, {2}] // MatrixForm

Have fun, Alexei

Alexei BOULBITCH, Dr., habil.

IEE S.A.

ZAE Weiergewan,

11, rue Edmond Reuter,

L-5326 Contern, LUXEMBOURG

Office phone :  +352-2454-2566

Office fax:       +352-2454-3566

mobile phone:  +49 151 52 40 66 44

e-mail: alexei.boulbitch at iee.lu<mailto:alexei.boulbitch at iee.lu>

```

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