Re: Simply but handy question

*To*: mathgroup at smc.vnet.net*Subject*: [mg124844] Re: Simply but handy question*From*: Christoph Lhotka <christoph.lhotka at fundp.ac.be>*Date*: Thu, 9 Feb 2012 05:38:21 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201202081029.FAA06451@smc.vnet.net>

hi, if you really need the matrix use a pattern rule like: Y/. x_Integer :> 1 /; NumericQ[x]&&x != 0 which will replace all non-zero values with one. if you just need to know the position of the zeros use Position[Y, 0, \[Infinity]] which will return a list of positions in Y which are zero. best, christoph On 02/08/2012 11:29 AM, jediwhelan 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>