"What am I doing wrong below?"
- "to go through each element of the string" your for-loop is fine
- "test if it's an 'a' or 'e' then add up each time" your tests don't test what you want them to test
The loop-counter, i, takes the numerical values 1,2,3,... You test whether this numerical value is equal to a character value. That smells. However, Matlab "thinks" that you want to compare the numerical value to the "ascii-value" of the character, e.g.
>> 97=='a'
ans =
1
Here 1 stands for true
Replace
i == 'a'
by
A(i) == 'a'
to compare the i:th character of A to the character, 'a'
