Can someone explain why I am getting the following error in my code?

function [g]=EdgeDetector_procedure(f)
[M,N]=size(f);
g=f;
m = 3; 
n = 3; 
a0 = (m-1)/2;
b0 = (n-1)/2;
for y = b0+1 : N-b0;
for x = a0+1 : M-a0;
  sum1 = 0;
  for k=-b0:b0;
  for j=-a0:a0;
      if ( f(x,y) == f (x+j,y+k) ) 
          sum1=sum1+1; 
      end;
  end;
  end;
  p=sum1/9;
  H=-plog(p);
  d=log(1/9);
  if(H<-d/9)
      g(x,y)=0;
  else
      g(x,y)=1; 
  end;
 end;
end;

?? Undefined function or method 'plog' for input arguments of type 'double'.

Error in ==> EdgeDetector_procedure at 20 H=-plog(p);

[Daniel Shub]

You get the error because MATLAB you use plog, but MATLAB doesn't know what it is.

Answer 1

[Image Analyst]

Try

H = -p .* log(p); % Calculate entropy.

By the way, there is an entropyfilt() entropy filter that you may want to check out.

[Daniel Shub]

I thought plog(p) was a typo of plot at first, but now I see that it is p.*log(p). Nice catch.