How to multiply one elements with rest of the elements in Galois field

Hi, I am working in Galois field, The generated field is GF( 2^4)

p=2;
n=4;
poly=[1 1 0 0 1];
field1=gftuple([-1:p^n-2]',poly,p);% it generates 16 elements
s2=[]; 
% i want to select one element of the field and then multiply all the elements of the field one by one with that element
for i=1:16
  a_1(i)=gfmul(5,i,field1); % here I am getting error
s2=[a_1];
end

First Question is how to multiply selected field element with the rest of the elements

My second question is when I select any random element of Galois field by using

field1(4) it gives incorrect answer