I cannot find the index of a specific element in an array?

I have an array of non-repeating elements, X. I need to find the index of a specific element, 1.5 in X. I am trying to do index=find(X==1.5). However it just does not work. I gives me a "empty matrix". Does this have to do with the elements in the array being decimal (float?) ? Please help me out.

[Robin]

btw, I am absolutely sure that 1.5 and the other elements I've tried with this method is actually in array X.

Answer 1

[Oleg Komarov]

Yes, floating point approximation ( faq6.1)

What you see is not what you get!

try this:

a = 0.2 + 0.1

>> a == 0.3
ans =
     0

sprintf('%.17f',a)

% Compare with threshold

abs(a - 0.3) < eps

[Robin]

ok I think I sort of understand what this is saying, but how does this help me? Like i get it that the sprintf function will print the float to like 17 digits, but how can I use this to equate the floating point numbers in my array X to 1.5?

[Oleg Komarov]

Reading the faq won't hurt just because it's in the brackets.

[Jan]

@Robin: This is an evergreen question. Ask Google for "Matlab faq6.1" to find more.

@Oleg: +1.