x = [1 2 3 2 3 4 2];
locations = find(x == 2)
The output of this find call has three elements (2, 4, and 7) since x contains three instances of the number 2 at locations 2, 4, and 7. If you only want to find the first or last instances find accepts options to do this.
firstTwo = find(x == 2, 1, 'first') % Find the first 1 instances of 2
lastTwoTwos = find(x == 2, 2, 'last') % Find the last 2 instances of 2
As a side note, testing for exact equality with floating-point values like 1.1 could give you results you don't expect (see especially the first example in the common problems section on that page.) In that scenario you probably want to compare with a tolerance or perhaps use the ismembertol function.
x = 0:0.1:1;
find(x == 0.3) % Not found
find(abs(x-0.3) <= eps) % found element 4 in x
