x = 0:0.5:20
find(x == 9.5)
However...
x = 0:0.1:20
find(x == 0.3)
[found, idx] = ismembertol(0.3, x)
It is typically (much more often than not) an error to use == to search for a value in a floating point array, with the exception of comparing something that has been extracted from the array. For example,
y = sin(x);
[maxy, idx_oneway] = max(y)
idx_anotherway = find(y == maxy)
max() and min() and indexing create bit-for-bit identical copies of values (except for weird nan values) so you can be sure that == will work for them. But you should rarely use == to compare non-integers to a list created with the : operator.
