M = 100;
N = 150;

C1 = real(planewave(10,0,100,150));
C2 = real(planechirp(2,-5,100,150,pi/4,4,4,-.5,3));
C3 = real(planewave(2,1,100,150));
C4 = real(planechirp(-.25,.5,100,150,pi/2.2,1,1,0,1));

subplot(221)
contour(C1)
contour(C2)
contour(C3)
contour(C4)

