fp_class.3

<B>Digital的Unix操作系统VAX 4.2源码</B>

.TH fp_class 3 RISC
.SH Name
fp_class \- classes of IEEE floating-point values
.SH Syntax
.nf
.B #include <fp_class.h>
.PP
.B int fp_class_d(double \fIx\fP);
.sp +.5
.B int fp_class_f(float \fIx\fP);
.fi
.SH Description
.NXR "fp_class routine" "RISC only"
These routines are used to determine the class of IEEE 
floating-point values.
They return one of the constants in the 
file 
.PN <fp_class.h>
and never cause an exception, even for signaling NaNs.
These routines are to implement the recommended function
.RI class( x )
in the appendix of the IEEE 754-1985 standard for binary floating-point
arithmetic.
The constants in
.PN <fp_class.h>
refer to the following classes of values:
.sp
.ta \w'FP_POS_DENORM\ \ 'u
\fBConstant	Class\fP
.sp .5
FP_SNAN	Signaling NaN (Not-a-Number)
.br
FP_QNAN	Quiet NaN (Not-a-Number)
.br
FP_POS_INF	+\(if (positive infinity)
.br
FP_NEG_INF	-\(if (negative infinity)
.br
FP_POS_NORM	positive normalized nonzero
.br
FP_NEG_NORM	negative normalized nonzero
.br
FP_POS_DENORM	positive denormalized
.br
FP_NEG_DENORM	negative denormalized
.br
FP_POS_ZERO	+0.0 (positive zero)
.br
FP_NEG_ZERO	-0.0 (negative zero)
.SH Also See
ANSI/IEEE Std 754-1985, 
IEEE Standard for Binary Floating-Point Arithmetic