# MATLAB does not recognize the matrix

7 views (last 30 days)
Mohammad Khan on 9 May 2020
Edited: Peng Li on 11 May 2020
I'm trying to create a GPA calculator for an assignment and I' m making use of matrix ii = 1:n, but MATLAB never makes use of this matrix and instead gives the message that the right and left sides are not compatible.
clc;clear
n = input('Number of courses taken this semester: ');
for kk = 1:n
u(kk) = input('Enter credit hour: ');
letter(kk) = input('Enter letter grade: ', 's');
if letter(kk) == 'A'
score(kk) = '4.00';
elseif letter(kk) == 'A-'
score = '3.67';
elseif letter(kk) == 'B+'
score(kk) = '3.33';
elseif letter(kk) == 'B'
score(kk) = '3.00';
elseif letter(kk) == 'B-'
score(kk) = '2.67';
elseif letter(kk) == 'C+'
score(kk) = '2.33';
elseif letter(kk) == 'C'
score(kk) = '2.00';
elseif letter(kk) == 'D'
score(kk) = '1.00';
elseif letter(kk) == 'F'
score(kk) = '0.00';
end
qlt_pts = u(kk) * score(kk);
end
fprintf('quality points: %f\n',qlt_pts);

Peng Li on 9 May 2020
qlt_pts = u(kk) * score(kk);
your score is a char array. so what do you want this multiplication to give you?
Mohammad Khan on 11 May 2020
THANK YOU WALTER! THIS IS PRECISELY WHAT I WAS LOOKING FOR!!!!
THAT IS EXACTLY WHAT I WAS LOOKING FOR!!!!

Rik on 9 May 2020
As Peng Li alludes to: your scores are char arrays. Why? It makes much more sense to store them are numeric arrays. That way you can also use an assignment like this:
score(kk)=2.33;
I would suggest you add an else with error handling. That way you can catch the user providing an incorrect letter grade. You also need to think if you want to keep all the letters that were entered. If you do, you are probably better off using a cell array.
A last point: if you want to compare char arrays you should be using the strcmp function.

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