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[x, y] = meshgrid(0 : 0.2 : 1);
z = sin(2 * pi * x) .* sin(2 * pi * y);
subplot(2, 2, 1)
surf(x, y, z)
[xi, yi] = meshgrid(0 : 0.02 : 1);
z1 = interp2(x, y, z, xi, yi, 'nearest');
z2 = interp2(x, y, z, xi, yi, 'bilinear');
z3 = interp2(x, y, z, xi, yi, 'bicubic');
subplot(2, 2, 2)
surf(xi, yi, z1)
subplot(2, 2, 3)
surf(xi, yi, z2)
subplot(2, 2, 4)
surf(xi, yi, z3)