is you objective function, you shouldn't run that. Create the definition of myfun into a separate file called myfun.m:
function f = myfun(x)
f = -x(1) * x(2) * x(3);
= [-1 -2 -2; ...
1 2 2];
And the rest of the code into a different script for example run_fmincon.m:
b = [0;72];
x0 = [10;10;10]; % Starting guess at the solution
[x,fval] = fmincon(@myfun,x0,A,b);
>> run_fmincon
