How to solve this problem " Error using gfmul The input elements must be integers between -Inf and P^M-2 over an extension field"

clc, clear all
m=8;
p=2;
primpoly = [1 0 0 0 1 1 1 0 1];
field=gftuple([-1:p^m-2]',primpoly,p);
gfmul(77,255,field)

Error using gfmul
The input elements must be integers between -Inf and P^M-2 over an extension field.

Answer 1

[Walter Roberson]

field=gftuple([-1:p^m-2]',primpoly,p);

When you use that form, starting with -1 as the value, you are asking for internal representation as exponents. Each input value later must be one of elements of -1:p^m-2 . In this case with p = 2 and m = 8 that is integers that are members of -1:254 (a total of 256 different values)

gfmul(77,255,field)

255 is not a member of -1:254 and so cannot be specified for multiplication when you are using that representation.