Re: slot argument weirdness

*To*: mathgroup at smc.vnet.net*Subject*: [mg83957] Re: slot argument weirdness*From*: Bill Rowe <readnewsciv at sbcglobal.net>*Date*: Wed, 5 Dec 2007 07:17:03 -0500 (EST)

On 12/4/07 at 4:29 AM, JLK2941 at yahoo.com (Jerry) wrote: >I have to produce some bulky matrices which are described by two >parameters and it seems the easiest way to produce them is as >follows (I took out all the complexity and just left in the slots to >illustrate my problem). v is the parameter array. >v = {2, 5}; >myMatrix=Apply[{{#1, #2}, {#2, #1}} &, v] >giving {{2, 5}, {5, 2}} and all is well. >But since the actual form in the first argument in Apply is really a >large messy thing, I thought I'd produce it just once in the >notebook and represent it with: >m = {{#1, #2}, {#2, #1}}; >But geez, this doesn't work at all: >MyMatrix2= Apply[m &, v] >gives {{#1, #2}, {#2, #1}} Are you using version 6 of Mathematica? If yes, did you notice the color of the slots was not the color Mathematica assigns by default to function arguements but instead was the color Mathematica uses to indicate a syntax error with your definition for m? Changing things to match the syntax Mathematca expects works, i.e., m = {{#1, #2}, {#2, #1}}&; makes m a function and In[4]:= Apply[m, v] Out[4]= {{2, 5}, {5, 2}} yields the desired result -- To reply via email subtract one hundred and four