Physicist here. One who believes -2**2 is negative. At 23:26 +0800 1/17/06, Audrey Tang wrote: >Several options: >- - Use whatever the underlying "num" semantics available
That's likely to be in hardware. It might even be hard to detect without looking at the NaN returned and that would be a waste of time. Some formulas can accept a NaN argument and still provide a correct result. At the worst they return a NaN to be tested for later >- - Always "fail" >- - Always "die" Those are non-conforming options See below. >- - Specify them to return some definite value. Only on a machine that doesn't do it in hardware or in some special perl function that's unlikely. >At this moment, Pugs defines them ad-hocly to: > > 0/0 == die "Illegal division by zero" <--- wrong. 1/0 should not > die either. > 0*Inf == NaN <--- reasonable but don't re-invent the NaN bit pattern > Inf/Inf == NaN <--- reasonable but don't re-invent the NaN bit pattern > Inf-Inf == NaN <--- reasonable but don't re-invent the NaN bit pattern > 0**0 == 1 <--- Not indeterminate. Answer is correct. > Inf**0 == 1 <--- Not indeterminate. Answer is correct. > 1**Inf == 1 <--- Not indeterminate. Answer is correct. <http://stevehollasch.com/cgindex/coding/ieeefloat.html> <http://en.wikipedia.org/wiki/Divide_by_zero> >The IEEE floating-point standard, supported by almost all modern processors, >specifies that every floating point arithmetic operation, including division >by zero, has a well-defined result. I can't seem to find the actual assigned NaN bit patterns for the above cases, <http://docs.sun.com/source/816-2465/iapgCreference.html> is helpful but doesn't get there. There may be multiple inf/inf returns in some cases depending on just which inf is involved. There are also NaN's for functions implemented in hardware like atan and exp. -- --> In Christianity, man can have only one wife. This is known as monotony. <--
