Assigning value to an element in vector

The problem is trivial but the code does not work. I wanted to replace 1 by -1 in a matrix

ip = [0 1 1 0;0 0 0 1]
X=find(ip == 1)
for i=1:length(X)
  ip(X(i))=-1
end

But this does not work and is beyond my understanding. Is there any logical error here?

[Azzi Abdelmalek]

Your code is correct

Is there any error message? If not what is the result?

Answer 1

[Walter Roberson]

Runs correctly for me.

In your actual code, is it possible that what you really have for "1" is not an integer? For example if you were searching for 1.3 ? If so then

http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

[xplore29]

this small script runs independently...thats true for mr as well. But in my big code this fails. And i am only dealing with integers and therefore getting into decimals is out of scope here.

i also tried

ip(ip==1)=-1

but this also fails in my main code.

[James Tursa]

What do you get for this:

isequal(fix(ip),ip)