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>