I'd like to define a function f(a,b)= product(product(p(a,b,c[i],d[j])^x[ij]*(1-p(a,b,c[i],d[j]))^(1-x[ij]),j=1..n),i=1..n) (The x's are known data, each 0 or 1, the c's and d's are also known.) Is there a way to do this without writing it out long-hand, say using a matrix of the x's and vectors of the c's and d's? Thanks.