Inquiries: Class and Sign(IM:PN)

Inside Macintosh: PowerPC Numerics / Part 2 - The PowerPC Numerics C Implementation: Chapter 7 - Numeric Data Types in C

Inquiries: Class and Sign
MathLib provides macros you can use to determine the class and sign of a floating-point value. All of these macros return type long int. They are listed in Table 7-3.Table 7-3 Class and sign inquiry macros Macro Value returned Condition fpclassify(x) FP_SNAN x is a signaling NaN FP_QNAN x is a quiet NaN FP_INFINITE x is $-$ or + FP_ZERO x is +0 or $-0$ FP_NORMAL x is a normalized number FP_SUBNORMAL x is a denormalized (subnormal) number isnormal(x) TRUE x is a normalized number isfinite(x) TRUE x is not $-$ , + , or NaN isnan(x) TRUE x is a NaN (quiet or signaling) signbit(x) 1 The sign bit of x is 1 (x is negative) 0 The sign bit of x is 0 (x is positive)

**Table 7-3 Class and sign inquiry macros**
Macro	Value returned	Condition
fpclassify(x)	FP_SNAN	`x` is a signaling NaN
	FP_QNAN	`x` is a quiet NaN
	FP_INFINITE	`x` is $-$ or +
	FP_ZERO	`x` is +0 or $-0$
	FP_NORMAL	`x` is a normalized number
	FP_SUBNORMAL	`x` is a denormalized (subnormal) number
isnormal(x)	TRUE	`x` is a normalized number
isfinite(x)	TRUE	`x` is not $-$ , + , or NaN
isnan(x)	TRUE	`x` is a NaN (quiet or signaling)
signbit(x)	1	The sign bit of `x` is 1 (`x` is negative)
	0	The sign bit of `x` is 0 (`x` is positive)