Re: Simply but handy question

*To*: mathgroup at smc.vnet.net*Subject*: [mg124846] Re: Simply but handy question*From*: Barrie Stokes <Barrie.Stokes at newcastle.edu.au>*Date*: Thu, 9 Feb 2012 05:39:03 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201202081029.FAA06451@smc.vnet.net>

Hi Paul How about: y = {{a, b}, {0, c}}; ClearAll[ somethingOrZero] somethingOrZero[x_] := If[ SameQ[ x, 0 ], 0, 1 ] Map[ somethingOrZero, y, {2} ]. Check the online Help for what the parameters of Map are, and what SameQ means. Barrie >>> On 08/02/2012 at 9:29 pm, in message <201202081029.FAA06451 at smc.vnet.net>, jediwhelan <jediwhelan at googlemail.com> 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

**References**:**Simply but handy question***From:*jediwhelan <jediwhelan@googlemail.com>