decide the size of matrix returned by gradient function

I want to find gradient of a function (x,y) in a loop and want to get a matrix of 10x10 size as the gradient matrix. I tried using - [___] = gradient(F,h) to set the distance between each point with different values of h. It doesn't seem to work and only returns a 100X100 matrix whatever I try (In the code below I get a 100x100 matrix for vfy1 and vfx1. How do I make the gradient command return only a 10X10 matrix?

Code-

x_grid = linspace(1,3,10);
y_grid = linspace(1,3,10);
for i = 1:1:length(x_grid)%rows
        x = x_grid(i);
        vpx_0 = 5;% initialize particle velocity in x and y directions
        vpy_0 = 0;
        for j = 1:1:length(y_grid) %columns
            y = y_grid(j);
            [vfy1,vfx1] = gradient(psi,10); % here is the gradient command
            vfy= -1*vfy1;
            vfx = vfx1;
            vpx(i,j) = sqrt((vpx_0).^2 + 2*g(1)*x);
            vpy(i,j) = -1*sqrt(vpy_0.^2 + abs(2*g(2)*y));
            vpx_0 = vpx(i,j);
            vpy_0 = vpy(i,j);
            vfx_sum = vfx_sum + vfx;%  has been pre-allocated (not shown here)
            vfy_sum = vfy_sum + vfy;%  has been pre allocated (not shown here)
        end
    end

[Rik]

Where do you define psi? That seems the most important part, since the rest of the code doesn't affect gradient.

[Sanjana Singh]

psi is defined above this piece of code as -

figure(1);
x = linspace(1,3);
y = linspace(1,3);
[x,y] = meshgrid(x,y);
psi = norm(vf)*(y-2+m*atan2(y-2,x-2+a)-m*atan2(y-2,x-2-a));
contour(x,y,psi,40);
hold on;

[Rik]

As psi is a 100x100 array, so is the output of gradient. The only thing the second input does is scaling the output. If you want a 10x10, you will have to enter a 10x10 matrix or downsample the result.

[Sanjana Singh]

Thank you, I didn't realize that. This worked!