forming a homogenous equation from the variables given in matlab

i have to construct a homogenous equation in the form of Ax = 0. where

x = (f11,f12,f13,f21,f22,f23,f31,f32,f33)T(T = transpose)

i am 10 correspondence point. each of those 10 points has x coordinate value and y coordinate value or i call xvals, yvals. so for my case n = 10. now i have to form A so that A is a nx9 matrix. then i have to do

svd(A,0)

can anyone help me that how to form the homogenous equation?