SCM_ROUND_TRUNC  2189 src/gauche.h       SCM_ROUND_TRUNC,
SCM_ROUND_TRUNC  1740 src/number.c       case SCM_ROUND_TRUNC: r = trunc(v); break;
SCM_ROUND_TRUNC  1742 src/number.c       case SCM_ROUND_TRUNC: r = (v < 0.0)? ceil(v) : floor(v); break;
SCM_ROUND_TRUNC   741 src/stdlib.c    SCM_RESULT = (Scm_Round(v, SCM_ROUND_TRUNC));