Comparison of Numeric Expressions.
Both arguments must be valid ground expressions at time of call.
1. static Int int_cmp(Int dif):
1. static Int flt_cmp(Float dif):
1. static Int a_cmp(Term t1, Term t2 USES_REGS):
1. Int Yap_acmp(Term t1, Term t2 USES_REGS):