Plotting an infinite integral

How do I plot an infinite integral? I am trying to plot a solution to Laplaces equation where -inf < x < inf.

What I have tried is:

f = 100;
b = 50;
x = linspace(-100, 100, .1); 
y = linspace(0, b, .01);
k = (0:.1:100);
kk = (-100:.2:100);
[K, KK] = meshgrid(k, kk);
T = zeros(length(x), length(y));

T = T + trapz(K, trapz(KK, sinh(K.*(b - y))./sinh(K.*b)*f.*...
            cos(K.*(KK - x))/pi));

imagesc(x, y, flipud(T))