get_norm_start()

gmp_RRmutable get_norm_start ( gmp_RR p, const Ring * R )

static

Definition at line 1137 of file mutable-matrix.cpp.

{
  if (R->get_precision() == 0)
    {
      ERROR("expected ring over an RR or CC");
      return nullptr;
    }
  gmp_RRmutable norm = getmemstructtype(gmp_RRmutable);
  mpfr_init2(norm, mpfr_get_prec(p));
  mpfr_ui_div(norm, 1, p, MPFR_RNDN);
  if (!mpfr_zero_p(norm))
    {
      ERROR("Lp norm only implemented for p = infinity");
      mpfr_clear(norm);
      return nullptr;
    }
  return norm;
}

References ERROR, Ring::get_precision(), getmemstructtype, and p.

Referenced by rawRingElementNorm().