Using the same approach as you developed so far, you would have to build index as a vector:
index = [] ;
for k = 1 : len
if vec(k) == key
index = [index, k] ;
end
end
Don't use i as a loop counter, because it should be reserved to complex notation. Now if you want to optimize a bit the approach, without using FIND, look at the following example:
>> key = 3 ;
>> vec = randi( 5, 1, 10 )
vec =
1 5 5 3 5 1 3 5 4 5
>> isEq = vec == key
isEq =
0 0 0 1 0 0 1 0 0 0
>> allInd = 1 : length( vec )
allInd =
1 2 3 4 5 6 7 8 9 10
>> allInd(isEq)
ans =
4 7
