How to perform iterations with a for loop technique or while technique ?

Hello all. I want to know how can I iterate a vector of (m,1) order to be iterated, say till the error become equals to e. and taking the initial guessed values. the problem is something mentioned below. Kindly Help ASAP. thank you!

V(m,1){kth iteration} = {1/Y(m,m)}[(P(m,1)-jQ(m,1))/V(m,1){(k-1)iteration}-sum(from j=1 to N){Y(m,j){V(j,1)kth iteration}}