Re: how to test where a list contains constant(s) or not

*To*: mathgroup at smc.vnet.net*Subject*: [mg91985] Re: how to test where a list contains constant(s) or not*From*: Albert Retey <awnl at gmx-topmail.de>*Date*: Tue, 16 Sep 2008 19:22:31 -0400 (EDT)*References*: <gal3iu$e0a$1@smc.vnet.net>

Hi, > case1: { a, b, c, Pi } gives true because of Pi > case2: { a, b, c, 0.0001} gives true because of 0.0001 > case3: { a, b, c, 2 + Pi I } gives ture becase of 2 + Pi I > case4: { a, b, c} gives false > > is this function right ? > > ComplexQ[z_] := NumericQ[ z ] || ( NumericQ[ z ] && SameQ[ Head[ z ], > Complex] ) > IsConstantsIn[ lstList_ ] := > Module[ { intLength }, > intLength = Length@Select[ lstList, ComplexQ[ # ]& ]; > If[ intLength > 0, Return[ True ], Return[ False ] ]; > Return[ False ]; > ] It probably does what you want, but I think it is way too complicated. Note that Complex numbers are Numeric by default, so there is no need for your ComplexQ-definition. If you think about seriously using Mathematica you should get familiar with its pattern matcher, otherwise you are missing its strongest part :-). If I correctly understood what you are after, the following leaves all the work for mathematica: IsConstantsIn[{___, _?NumericQ, ___}] := True IsConstantsIn[___] := False the first definition gives True, if the argument to IsConstantsIn is a list containing at least one numeric element at any position. The second definition ensures that IsConstantsIn will return False in any other case. To handle other cases, e.g. expressions that are not lists you can easily extend by adding additional definitions. Finally I think the name of your function could probably changed to reflect more clearly what exactly it is doing, e.g. IsNumericIn or HasNumericElement. Mathematica has the posibility to define attributes to symbols, among these attributes is Constant, so IsCOnstantsIn would mislead me in thinking it has something to do with that... hth, albert