I need help with using a function file for assinging letter grades.

I'm using a fuction file to transport inputs of numerical grades into output letter grades.

Here are my two scripts

%Script 1: A1_3_8.m
%Problem 3.8A
format compact
score=input('Enter numerical grade:');
grade= lettergrade(score);
disp(grade);

%Script 2: lettergrade.m
format compact
function grade= lettergrade(score)
array=['A','B','C','D','F'];
if score < 0 || score > 100
    disp('Invalid')
elseif score >= 90
    grade=array(1);
elseif score >= 80
    grade=array(2);
elseif score >= 70
    grade=array(3);
elseif score >= 60
    grade=array(4);
else
    grade=array(5);
end
end

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I am not sure of what I am doing and need help with using a function file properly.

Answer 1

[Walter Roberson]

format compact
function grade= lettergrade(score)

When you have an executable line before the first function line, then that makes the file a script file rather than a function file. script files cannot be called as functions, such as your

grade= lettergrade(score);

Also, there is a restriction that a script file cannot have a function with the same name as the script -- so function lettergrade cannot be inside script file lettergrade.m

format statements are not needed in every file: the last format executed is obeyed until you execute another format or quit MATLAB. You especially do not need a format statement inside code that does not display any output.