problem in return code

Hi, I worked a program to my final project in university; but there a problem in my m file... I need to return to start of my program in one case, but i can't... my program is:

function out = firstecg(x)
a=imread(x);
b=imread('normal.png');

a=rgb2gray(a);
b=rgb2gray(b);
a=im2bw(a);
b=im2bw(b);

%per diff between a and b
w=0;
const=size(a);
row=const(1);
column=const(2);
constant=row*column;
for i=1:row
  for j=1:column
    y=xor(a(i,j),b(i,j));
    if y~=0
        w=w+1;
    end
  end
end

perab=w/constant;
perab;
perno1=0.0023;
perno2=0.0040;
if ((0.0005>= perab)& (perab>= 0))
    disp('no problem')
    return %my problem is here
else
.
.
.
end %end of my program

when I run the program and in a case of return ... the result is just "no problem" , I need to return to a start of function but i can't, "the Matlab is not applied return in any case and that is a problem"

please help my

[Jan]

What does this mean: "return to start of function"?

[Tariq Nazzal]

I mean go to start of program and rerun the program again and again

Answer 1

[Babak]

"return" command, ends the execution of the code.

"return" does not mean that the code is going to start from the beginning of the function and start running it again and again....

[Tariq Nazzal]

aha, what the code to applied it , if "return" code is wrong....

[Babak]

Change that block of your code to this and see if it works:

 if ((0.0005>= perab)& (perab>= 0))
     disp('no problem')
     % Here is where you need to call this function again
     % You need to set the input and output arguments of the next
     % line depending on your case

     out = firstecg(x)

 else

[Tariq Nazzal]

thanks to you, I'm try it and it the correct answer, thanks you again...

Answer 2

[Jan]

At first I suggest to simplify the computations:

% per diff between a and b
perab = sum(xor(a(:), b(:)) ~= 0) / numel(a);

[Tariq Nazzal]

that is the best, and thank to simplified my program, but what about "return"...

[Jan]

Well, I do not have any clue, why you use "return", when you want a loop.

perab = 0;
while 0 <= perab & perab <= 0.0005
  ...  Her is your program
end

But what do you expect? You read in the same picture files and get the same results in each iteration. Therefore it is not clear, what you want to achieve.

[Tariq Nazzal]

Other friends answer the problem by calling the function again , your question is true, but the picture is always refresh and refresh every time from device sending the picture to my path folder , and delete last picture from the folder, and saving new picture with the name of deleted picture.

thanks to you