new; cls; /* Calculates polynomial a x polynomial b in base NN */
a={1,2,3};
b={1,1,2};
NN=3;
print/rz polymulb(a,b,NN);


proc polymulb(a,b,NN);
   local ra,rb,c,i,j,x;
   ra=rows(a); rb=rows(b);
   c=zeros(ra+rb-1,1);
   i=0;
   do while i<=ra+rb-2;
      x=0;
      j=maxc(0|i-ra+1);
      do while j<=minc(rb-1|i);
         x=(x+a[i-j+1]*b[j+1])%NN;
         j=j+1;
      endo;
      c[i+1]=x;
      i=i+1;
   endo;
   retp(c);
endp;