Description of the function

*To*: mathgroup at smc.vnet.net*Subject*: [mg13746] Description of the function*From*: "Toshiyuki Meshii" <tm60 at cornell.edu>*Date*: Wed, 19 Aug 1998 01:38:34 -0400*Sender*: owner-wri-mathgroup at wolfram.com

Hello, I want to make a least square fit of some data set A{x1, x2, f}. The function to be fitted is f[x1_, x2_, a_, b_] = a*x1 + b*x2^2 When I define a error function erf[a_,b_,c_,d_]= Sum[ ( f[ A[[j]][[1]], A[[j]][[2]],a,b]-A[[j]] )^2, {j,6} ] the function erf obtained does not come with a equation written down in a, b. Instead, it comes with bunch of f[ ]. How can I obtain function erf in a direct form? -Toshi