Why is >= not defined

A_cutoff=input('Please enter you lowest grade for an A...');
B_cutoff=input('Please enter you lowest grade for an B...');
C_cutoff=input('Please enter you lowest grade for an C...');
D_cutoff=input('Please enter you lowest grade for an D...');
filename=input('please input file name');
[num, text, raw]=xlsread(filename);
b=[];
[c,d]=size(raw);
b=raw(:,d);
[k,l]=size(b);
B=[];
for m=1:k
for n=1:l
    if b>=A_cutoff
        B(k,n)='A';
    elseif b>=B_cutoff
        B(k,n)='B';
    elseif b>=C_cutoff
        B(k,n)='C';
    elseif b>=D_cutoff
        B(k,n)='D';
    elseif b>=0
        B(k,n)='F';
    end
end
end

when i run this script it gives me the error of

"Undefined operator '>=' for input arguments of type 'cell'."

can not figure out why though. It works in other codes but not this one.

[William Dever]

Solved my own problem. i rewrote it and now it is working.

Answer 1

[Walter Roberson]

You have

b=raw(:,d);

the raw output from xlsread is returned as a cell array, not as a numeric array. If you want the numeric array you should be looking at the num output.

Hint: notice that you never change b inside your for loops. Perhaps you should be examining the content of individual cells. But before doing a numeric comparison you have to know that what you are comparing to is numeric rather than string, because cell arrays can contain strings...