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Re: Simply but handy question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124883] Re: Simply but handy question
  • From: Paul Whelan <jediwhelan at googlemail.com>
  • Date: Fri, 10 Feb 2012 05:57:49 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <7BB0E96E72E84E41B24A1FF8ED13F5E6156AA9F3DA@IE2RD2XVS581.red002.local>

Hi Alexei,

this is a nice solution ! thanks

On Thu, Feb 9, 2012 at 8:52 AM, Alexei Boulbitch <Alexei.Boulbitch at iee.lu>wrote:

> 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****
>
> ** **
>
> ** **
>


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