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IEEE Special Values

CMU Common Lisp supports the IEEE infinity and NaN special values. These non-numeric values will only be generated when trapping is disabled for some floating point exception (see section float-traps), so users of the default configuration need not concern themselves with special values.

[Constant]
Last message occurs repeats timesextensions:
short-float-positive-infinity extensions:short-float-negative-infinity
extensions:single-float-positive-infinity
extensions:single-float-negative-infinity
extensions:double-float-positive-infinity
extensions:double-float-negative-infinity
extensions:long-float-positive-infinity
extensions:long-float-negative-infinity

The values of these constants are the IEEE positive and negative infinity objects for each float format.

[Function]
extensions: float-infinity-p
x

This function returns true if x is an IEEE float infinity (of either sign.) x must be a float.

[Function]
extensions: float-nan-p
x extensions:float-trapping-nan-p x

float-nan-p returns true if x is an IEEE NaN (Not A Number) object. float-trapping-nan-p returns true only if x is a trapping NaN. With either function, x must be a float.



Peter Van Eynde 2000-02-08