NAN(2) System Calls Manual NAN(2)NAME
NaN, Inf, isNaN, isInf - not-a-number and infinity functions
SYNOPSIS
#include <u.h>
#include <libc.h>
double NaN(void)
long Inf(int)
int isNaN(double)
int isInf(double, int)
DESCRIPTION
The IEEE floating point standard defines values called `not-a-number' and positive and negative `infinity'. These values can be produced
by such things as overflow and division by zero. Also, the library functions sometimes return them when the arguments are not in the
domain, or the result is out of range.
NaN returns a double that is not-a-number. IsNaN returns true if its argument is not-a-number.
Inf(i) returns positive infinity if i is greater than or equal to zero, else negative infinity. IsInf returns true if its first argument
is infinity with the same sign as the second argument.
SOURCE
/sys/src/libc/$objtype/nan.c
NAN(2)
Check Out this Related Man Page
SCALB(3) Linux Programmer's Manual SCALB(3)NAME
scalb, scalbf, scalbl - multiply floating-point number by integral power of radix (OBSOLETE)
SYNOPSIS
#include <math.h>
double scalb(double x, double exp);
float scalbf(float x, double exp);
long double scalbl(long double x, double exp);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
scalb(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500
scalbf(), scalbl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
DESCRIPTION
These functions multiply their first argument x by FLT_RADIX (probably 2) to the power of exp, that is:
x * FLT_RADIX ** exp
The definition of FLT_RADIX can be obtained by including <float.h>.
RETURN VALUE
On success, these functions return x * FLT_RADIX ** exp.
If x or exp is a NaN, a NaN is returned.
If x is positive infinity (negative infinity), and exp is not negative infinity, positive infinity (negative infinity) is returned.
If x is +0 (-0), and exp is not positive infinity, +0 (-0) is returned.
If x is zero, and exp is positive infinity, a domain error occurs, and a NaN is returned.
If x is an infinity, and exp is negative infinity, a domain error occurs, and a NaN is returned.
If the result overflows, a range error occurs, and the functions return HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively, with a sign the
same as x.
If the result underflows, a range error occurs, and the functions return zero, with a sign the same as x.
ERRORS
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
Domain error: x is 0, and exp is positive infinity, or x is positive infinity and exp is negative infinity and the other argument is not a
NaN
An invalid floating-point exception (FE_INVALID) is raised.
Range error, overflow
An overflow floating-point exception (FE_OVERFLOW) is raised.
Range error, underflow
An underflow floating-point exception (FE_UNDERFLOW) is raised.
These functions do not set errno.
CONFORMING TO
scalb() is specified in POSIX.1-2001, but marked obsolescent. POSIX.1-2008 removes the specification of scalb(), recommending the use of
scalbln(3), scalblnf(3), or scalblnl(3) instead. The scalb() function is from 4.3BSD.
scalbf() and scalbl() are unstandardized; scalbf() is nevertheless present on several other systems
SEE ALSO ldexp(3), scalbln(3)COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2009-03-15 SCALB(3)