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44 lines
931 B
Groff
44 lines
931 B
Groff
.TH NAN 3
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.SH NAME
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NaN, Inf, isNaN, isInf \- not-a-number and infinity functions
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.PP
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.ta \w'\fLdouble 'u
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.B
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double NaN(void)
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.PP
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.B
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double Inf(int)
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.PP
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.B
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int isNaN(double)
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.PP
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.B
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int isInf(double, int)
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.SH DESCRIPTION
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The IEEE floating point standard defines values called
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`not-a-number' and positive and negative `infinity'.
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These values can be produced by such things as overflow
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and division by zero.
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Also, the library functions sometimes return them when
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the arguments are not in the domain, or the result is
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out of range.
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.PP
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.I NaN
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returns a double that is not-a-number.
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.I IsNaN
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returns true if its argument is not-a-number.
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.PP
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.IR Inf ( i )
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returns positive infinity if
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.I i
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is greater than or equal to zero,
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else negative infinity.
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.I IsInf
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returns true if its first argument is infinity
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with the same sign as the second argument.
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.SH SOURCE
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.B \*9/src/lib9/nan.c
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