C:\>perl -MMath::MPFR=":mpfr" -le "$op = Math::MPFR->new(-9117 ** 3); Rmpfr_cbrt($op, $op, MPFR_RNDN); print $op;" -9.117e3 #### C:\>perl -MMath::MPFR=":mpfr" -le "$op = Math::MPFR->new(-9117 ** 3); Rmpfr_rootn_ui($op, $op, 3, MPFR_RNDN); print $op;" -9.117e3