how to caculate covariance matrix?

i tried to calculate covariance of matrix but an error appeared:

here is my matrix (3*3):

m=

26 197 27 197 28 197
26 196 27 196 28 196
26 195 27 195 28 195

where(26,197) describe piwel's position

and this is the error:

Error using bsxfun
Mixed integer class inputs are not supported.

Error in cov (line 154)
xc = bsxfun(@minus,x,sum(x,1)/m); % Remove mean

Error in fourptm (line 155)
c=cov(m)

Answer 1

[Walter Roberson]

cov(double(m))

[bay rem]

thank you so much i already tried it, but Is it right to find such result:

       0     0     0     0     0     0
       0     1     0     1     0     1
       0     0     0     0     0     0
       0     1     0     1     0     1
       0     0     0     0     0     0
       0     1     0     1     0     1

[Walter Roberson]

Yes.