1. The problem statement, all variables and given/known data I am trying to graph the flux density field between two infinite line charges located at y = 1 and y = -1 2. Relevant equations I am trying to do it using the equation for a line charge that I got from lecture notes. The above equation is derived from this: Here is the proof http://puu.sh/g4E0V/68d2790871.png [Broken] My friend successfully graphed the field using this equation and using a nested loop to sum the pieces of the line up at each point, but I chose another way and am having trouble. 3. The attempt at a solution I tried doing it by solving using the line charge field equation at every point rather than using a loop, but ended up with a different wrong result. This is my code. In my code what I call x and y are respectively z and p in that yellow diagram above. min = -5; max = 5; num = 50; step = (max - min) / (num-1); [X,Y]=meshgrid(-5:step:5,-5:step:5);%build arrays of plot space Fx=zeros(num,num);%x component of flux density Fy=zeros(num,num);%y component of flux density pL1=1e-6;%top line charge density pL2=-1e-6;%bottom line charge density for i=1:num for j=1:num %cos = x / h %sin = y / h x = X(i,j); y = Y(i,j); Fy(i,j) = (pL1 / (2*pi*(y-1))) * 1; Fx(i,j) = (pL1 / (2*pi*(y-1))) * 0; Fy(i,j) = Fy(i,j) + (pL2 / (2*pi*(y+1))) * 1; Fx(i,j) = Fx(i,j) + (pL2 / (2*pi*(y+1))) * 0; end end quiver(X,Y,Fx,Fy) Help is much appreciated.