??? Undefined function or method 'conv2' for input arguments of type 'cell'.

Hi,

I am trying this code but having real frustrating erorr again and again. Could any one please let me know what I am doing wrong.

Here is the code

clear all; clc;
sigma = 1;
radius = 1;
threshold = 1000;
size = 2 *radius +1;

dx= { -1 0 1 ;  -1 0 1; -1 0 1};
dy = dx;

g= fspecial ( 'gaussian', max(1, fix(6*sigma)), sigma);

source = imread ('cow2.jpg');

im = source (: , : , 1);

Ix = conv2 (im, dx, 'same');
Iy= conv2 (im, dy, 'same');

Ix2= conv2 (Ix. ^2, g, 'same');
Iy2= conv2 (Iy. ^2, g, 'same');
Ixy = conv2 (Ix. *Iy, g, same');

harris = (Ix2.*Iy2  - I xy.^2)./ (Ix2+Iy2 +eps);

mx = ordfilt2(harris, size. ^2, ones(size));

harris = (harris ==mx) & (harris > threshold);

(rows, cols) =- find(harris);
figure, image(source), axis image, colormap(gray). hold on.
plot(cols, rows, 'ya'), title('corner detected');