Undefined function or variable 'm'

I'm newer using matlab I wrote this code,but i have a error Plz help me,thanks

A=imread('21_training.tif');
B=A(:,:,2);
%opening disk = 3
se=strel('disk',3);
C=imopen(B,se);

%co-occurrence matrix
glcm=graycomatrix(C,'NumLevel',256);
p=glcm/sum(glcm(:));

%mean pi,pj and standard deviation pi,pj (mean pi=mean pj)
for i=1:256
  for j=1:256
      m=m+double(i).*p(i,j);
  end
end

error: Undefined function or variable 'm'

Answer 1

[ES]

It could help if you could format your code using the {}Code button in the question edit window. the Problem is m is not defined. You have done

m=m+(something)

in the first iteration (i=1 and j=1), matlab tries to add value of double(i).*p(i,j) to m. but it does not know what m is.

Initialize m to something (say 0) and try.

[Huy]

thanks

Answer 2

[Azzi Abdelmalek]

The for loop

m=0
for i=1:256
for j=1:256
    m=m+double(i).*p(i,j);
end
end

can be replaced by

m=sum(sum(repmat((1:256)',1,256).*p))

%or

m=sum(sum(bsxfun(@(x,y) x.*y,p,(1:256)')));

[Huy]

thanks

Answer 3

[Andrei Bobrov]

m = sum((1:256)*p)

[Huy]

thanks