Re: Testing for IEEE infinity and NaN?

On Thu, 15 Jun 2006 17:15:41 UTC, Raymond Toy <raymond.toy@xxxxxxxxxxxx> wrote:

Is there a "fast" way to check if an IEEE floating-point number is
infinity? I pretty sure that NaN can be test easily by doing x = x,
which is always true, except if x i NaN. Is there something just as
easy for infinity? Or do I have to look at the exponent of the number
to figure that out?

In C99 terms:
#define isnan(x) ( (x) != (x) )
#define isinf(x) ( !isnan(x) && isnan( (x) - (x) ) )

---
Fred J. Tydeman Tydeman Consulting
tydeman@xxxxxxxxx Testing, numerics, programming
+1 (775) 358-9748 Vice-chair of J11 (ANSI "C")
Sample C99+FPCE tests: http://www.tybor.com
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