I am writing a code that, among other things, iteratively solves a set of non-linear algebraic equations. I am using Newton's method. f1(x1,x2,...,xN)=0 f2(x1,x2,...,xN)=0 ..... fN(x1,x2,...,xN)=0 The difficulty arises because f1, f2, ..., fN are known at the time of compilation. In fact, the number of equations N is also unknown. They are provided by the user during run-time either via an input file, or using the keyboard. Therefore I cannot hard-code them into the source code. All I know about the functions are that they are a weighted sum of known functions. i.e. for i=1,2,...,N, f_i(x1,x2,...,xN)=a1*g1(x1,x2,...,xN)+a2*g2(x1,x2,...,xN)+... where the functional forms of g1, g2, ... are known. How do I pass f1, f2, .., fN to the Newton's iteration subroutine? Is it possible at all, and what is the syntax? I guess this is a general programming question, but since I am using C+ + in this case, I am posting this question here. dsv