Calculate power with large number in matlab

Question

I want to calculate for example 257^150 but matlab shows until 257^126. I want to find the exponent "x" in order to compute the modulus. For example the power which gives (257^x mod 1009) = 369. Thanks.

Answer 1

Think about the problem and how you would solve it. You know hat mod(x,42) is 23 . What is the remainder of 7*x ? Its mod(7*42,23)

Put into code:

a=257;
m=1009;
s=369;
r=1;
x=0;
while(not(r==s))
    x=x+1;
    r=mod(r*a,m);
end