MATLAB: Undefined function or variable “sum”.

sumundefined function or variable

I have the following code:
function outdata=pixelate(fname)
imdata=rgb2gray(imread(fname));
outdata=zeros(size(imdata))+255;
for i=1:size(imdata,1)
  indi=[i-1 i i+1];
  indi(indi<=0)=[];
  indi(indi>size(imdata,1))=[];
  isum=sum(indi,:);
  isize=length(indi);
  for j=1:size(imdata,2)
    indj=[i-1 i i+1];
    indj(indj<=0)=[];
    indj(indj>size(imdata,1))=[];
    jsize=length(indj);
    avg=sum(isum(indj))/(isize*jsize);
    if avg<255*0.5
      outdata(i,j)=0;
    end
  end
end
end
The code analyzer generates a warning on line 8 saying 'The variable 'sum' might be used before it is defined.' The when I run the code I get the following:
Undefined function or variable "sum".
Error in pixelate (line 10)
  isum=sum(indi,:);
After a little googling, I tried the following while in debug mode (stopped at line 8):
K>> which sum
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@uint8\sum)  % uint8 method

K>> which -all sum
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@uint8\sum)    % uint8 method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@uint16\sum)   % Shadowed uint16 method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@uint32\sum)   % Shadowed uint32 method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@uint64\sum)   % Shadowed uint64 method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@int8\sum)     % Shadowed int8 method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@int16\sum)    % Shadowed int16 method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@int32\sum)    % Shadowed int32 method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@int64\sum)    % Shadowed int64 method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@single\sum)   % Shadowed single method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@char\sum)     % Shadowed char method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@double\sum)   % Shadowed double method
built-in (C:\Program Files\MATLAB\R2014a\toolbox\matlab\datafun\@logical\sum)  % Shadowed logical method
C:\Program Files\MATLAB\R2014a\toolbox\symbolic\symbolic\@sym\sum.m            % Shadowed sym method
C:\Program Files\MATLAB\R2014a\toolbox\matlab\timeseries\@timeseries\sum.m     % Shadowed timeseries method
K>> whos sum
K>>
I have tried restarting matlab. I have also tried copying the code and pasting it to a new file. I have not tried restarting the computer, though I will do that when it will not hurt too much.

Best Answer

check the syntax of the sum() function
Syntax
B = sum(A)
B = sum(A,dim)
B = sum(..., 'double')
B = sum(..., dim,'double')
B = sum(..., 'native')
B = sum(..., dim,'native')
Your statement isum=sum(indi,:) is invalid. Maybe you mean isum=sum(indi(:));
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