PROLOG  NAME  SYNOPSIS  DESCRIPTION  RETURN VALUE  ERRORS  EXAMPLES  APPLICATION USAGE  RATIONALE  FUTURE DIRECTIONS  SEE ALSO  COPYRIGHT 

SCALBLN(3P) POSIX Programmer's Manual SCALBLN(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
scalbln, scalblnf, scalblnl, scalbn, scalbnf, scalbnl — compute exponent using FLT_RADIX
#include <math.h> double scalbln(double x, long n); float scalblnf(float x, long n); long double scalblnl(long double x, long n); double scalbn(double x, int n); float scalbnf(float x, int n); long double scalbnl(long double x, int n);
The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2008 defers to the ISO C standard. These functions shall compute x * FLT_RADIXn efficiently, not normally by computing FLT_RADIXn explicitly. An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is nonzero or fetestexcept(FE_INVALID  FE_DIVBYZERO  FE_OVERFLOW  FE_UNDERFLOW) is nonzero, an error has occurred.
Upon successful completion, these functions shall return x * FLT_RADIXn. If the result would cause overflow, a range error shall occur and these functions shall return ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL (according to the sign of x) as appropriate for the return type of the function. If the correct value would cause underflow, and is not representable, a range error may occur, and scalbln(), scalblnf(), scalblnl(), scalbn(), scalbnf(), and scalbnl() shall return 0.0, or (if IEC 60559 FloatingPoint is not supported) an implementationdefined value no greater in magnitude than DBL_MIN, FLT_MIN, LDBL_MIN, DBL_MIN, FLT_MIN, and LDBL_MIN, respectively. If x is NaN, a NaN shall be returned. If x is ±0 or ±Inf, x shall be returned. If n is 0, x shall be returned. If the correct value would cause underflow, and is representable, a range error may occur and the correct value shall be returned.
These functions shall fail if: Range Error The result overflows. If the integer expression (math_errhandling & MATH_ERRNO) is nonzero, then errno shall be set to [ERANGE]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is nonzero, then the overflow floatingpoint exception shall be raised. These functions may fail if: Range Error The result underflows. If the integer expression (math_errhandling & MATH_ERRNO) is nonzero, then errno shall be set to [ERANGE]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is nonzero, then the underflow floatingpoint exception shall be raised. The following sections are informative.
None.
On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other, but at least one of them must be nonzero.
These functions are named so as to avoid conflicting with the historical definition of the scalb() function from the Single UNIX Specification. The difference is that the scalb() function has a second argument of double instead of int. The scalb() function is not part of the ISO C standard. The three functions whose second type is long are provided because the factor required to scale from the smallest positive floatingpoint value to the largest finite one, on many implementations, is too large to represent in the minimumwidth int format.
None.
feclearexcept(3p), fetestexcept(3p) The Base Definitions volume of POSIX.1‐2008, Section 4.19, Treatment of Error Conditions for Mathematical Functions, math.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology  Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.12008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/manpages/reporting_bugs.html .
IEEE/The Open Group 2013 SCALBLN(3P)
Pages that refer to this page: math.h(0p), ilogb(3p), logb(3p)