_mode=POLY;
_cpu=1;
_language=en$
_modenum=NUMRATMP$

macro sekimat[p1,m,p2,n]{

  private a,b,l,s,sekimat0,ii,j,q,tmp,f,g,h$

  if (m>=n) then{
    a=p1$
    b=p2$ 
    l=m$
    s=n$
  }
  else{
    a=p2$
    b=p1$
    l=n$
    s=m$
  }$

  dim sekimat0[1:l,1:l]$

  for ii=0 to l-s-1 {
    for j=0 to s {
      sekimat0[ii+1,j+ii+1]=coef_ext(b,(x,j))$
    }$
  }$

  b=x^(l-s)*b$

  div(a,x^l,q,f)$
  div(b,x^l,q,g)$
  h=coef_ext(a,(x,l))*g-coef_ext(b,(x,l))*f$
  for j=0 to l-1 {
    sekimat0[2*l-s-l+1,j+1]=coef_ext(h,(x,j))$
  }$

  for ii=l-1 to l-s+1 step(-1) {
    div(h,x^(l-1),q,tmp)$
    h=x*tmp+coef_ext(a,(x,ii))*g-coef_ext(b,(x,ii))*f$
    for j=0 to l-1 {
      sekimat0[2*l-s-ii+1,j+1]=coef_ext(h,(x,j))$
    }$
  }$ 
  
  return(sekimat0)$

}$

p=x^9+x^8+a7*x^7+a6*x^6+a5*x^5+a4*x^4+a3*x^3+a2*x^2+a1*x+a0$
q=deriv(p,x)$

time_s;
m9=%sekimat[p,9,q,8]$
w=det(m9,"minor")$
size(w);
time_l;