SCM_ROUND_FLOOR  2187 src/gauche.h       SCM_ROUND_FLOOR,
SCM_ROUND_FLOOR  1736 src/number.c       case SCM_ROUND_FLOOR: r = floor(v); break;
SCM_ROUND_FLOOR   703 src/stdlib.c    SCM_RESULT = (Scm_Round(v, SCM_ROUND_FLOOR));