for if matrix

for i=1:n-1
    for j=1:n-1
        for r=1:332
            if i + r  > 333
              data(i+r,:)=0;
                    *else if i-r = < 0
                            data(i-r,:)=0;*
                            else if j+r > 333
                                    data(:,j+r)=0;
                                     else if j-r = < 0
                                            data(:,j-r)=0;
                                         end
                                end
                          end
            end

          end
      end
  end

Please tell me how I can correct the error at i-r = < 0

[Jan]

Which error?

Answer 1

[Walter Roberson]

Change the '= <' to '<=' (without the apostrophes.)

http://www.mathworks.com/help/techdoc/ref/le.html

[Amit]

i do the correction, but there is one more error, plz tell me how i can correct it

??? Subscript indices must either be real positive integers or logicals.

data(i-r,:)=0;

[Walter Roberson]

Your code has (after correction to <= )

else if i-r <= 0

data(i-r,:)=0;

But if i-r <= 0 as found by the "if" test, then i-r is 0 or negative, and you are then trying to use that 0 or negative value as a subscript of "data".

Perhaps you wanted to test if i-r > 0 ?

You have the same problem with all of your "if" tests: you check for something that would be out of range, and when you find it, you use the out-of-range value!

[Amit]

thanks, yet there is one problem doing this

else if i-r > 0

data(i-r,:);

??? Attempted to access data(0,1); index must be a positive

integer or logical.

[Walter Roberson]

That would happen if your test was

elseif i-r >= 0

but that cannot happen if your test is

elseif i-r > 0

[Amit]

??? Attempted to access data(0,1); index must be a positive

integer or logical.

Error in ==> file at 30

s=s+data(i+r,j)+data(i-r,j)

[Walter Roberson]

That involves code you have not posted above. I would need to see the updated code.

[Amit]

The whole code look like this

n=length(data(1,:));

for i=1:n-1

for j=1:n-1

for r=1:332

if i + r > 333

data(i+r,:)=0;

else if i-r > 0

data(i-r,:);

else if j+r > 333

data(:,j+r)=0;

else if j-r > 0

data(:,j-r);

end

end

end

end

s=s+data(i+r,j)+data(i-r,j)

end

end

end

[Walter Roberson]

Your line s=s+data(i+r,j)+data(i-r,j) is outside of any of your "if" tests, so it is going to always be executed. It will cause a problem if i-r is 0 or negative.

[Amit]

Thanks Walter

Answer 2

[Jan]

Do you really have a space between the = and the < ? If so, remove it.

Please add the error message. Otherwise we have to guess, what your problem might be.

[Amit]

Error: File: file.m Line: 19 Column: 33

The expression to the left of the equals sign is not a

valid target for an assignment.