Re: Building a list

*To*: mathgroup at smc.vnet.net*Subject*: [mg47141] Re: [mg47114] Building a list*From*: Tomas Garza <tgarza01 at prodigy.net.mx>*Date*: Sat, 27 Mar 2004 01:34:46 -0500 (EST)*References*: <200403260856.DAA22958@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi Mark, Perhaps this will help: In[1]:= xlist = {x1, x2, x3}; In[2]:= mat = Outer[List, xlist, xlist] Out[2]= {{{x1,x1},{x1,x2},{x1,x3}},{{x2,x1},{x2,x2},{x2,x3}},{{x3,x1},{x3,x2},{x3, x3}}} In[3]:= ((f[a, b, Sequence @@ #] & ) /@ # & ) /@ mat Out[3]= {{f[a,b,x1,x1],f[a,b,x1,x2],f[a,b,x1,x3]},{f[a,b,x2,x1],f[a,b,x2,x2], f[a,b,x2,x3]},{f[a,b,x3,x1],f[a,b,x3,x2],f[a,b,x3,x3]}} Tomas Garza Mexico City ----- Original Message ----- From: "Mark Coleman" <mark at markscoleman.com> To: mathgroup at smc.vnet.net Subject: [mg47141] [mg47114] Building a list > Greetings, > > I've got a relatively simple function f[a_,b_,c_,d_], where a and b are > integers and c and d are lists (of reals), and f returns a real. > > I need to evaluate f on (potentially long) sets of lists and calculate > a square "matrix" from the possible permutations of the elements in the > lists. For instance > > If > > xlist={x1,x2,x3} > > > I need to calculate > > {{f[a,b,x1,x1],f[a,b,x1,x2],f[a,b,x1,x3]},{f[a,b,x2,x1],f[a,b,x2,x2],f[a > ,b,x2,x3]},{f[a,b,x3,x1],f[a,b,x3,x2],f[a,b,x3,x3]}} > > Note that f[a,b,c,d] does not equal f[a,b,d,c]. > > My first reaction was that Outer[] might do this, but I cannot seem to > get it to work. I'd appreciate any suggestions. > > Thanks, > > Mark > >

**References**:**Building a list***From:*Mark Coleman <mark@markscoleman.com>