Hi, suppose I have two vectors, one in the i direction and the other in j direction, i is horizontal and j vertical. The first vector Vi = 5i and the second vector Vj = 2j. If we sum this vectos it results in one vector that have module and phase. I found the module by Vij = ( 5^2 + 2^2 ) ^ (1/2) = 5.3852. But what about the phase? I think it was atan(y/x), but in case y=0 or x=0, it let me in troubles.