sortsv(AvARRAY(data), arrayLen+1, Perl_sv_cmp);
to
sortsv(AvARRAY(data), arrayLen+1, numerical_cmp);

???
I32 numerical_cmp(SV* sv1,SV* sv2) {

  double num1;
  double num2;

  num1 = (double)*sv1;
  num2 = (double)*sv2;

  if (num1 == num2) {
    return 0;
  }
  else if (num1 > num2) {
    return 1;
  }
  else {
    return -1;
  }
}