scalbln(), scalblnf(), scalblnl()

Updated: April 19, 2023

Load the exponent of a radix-independent floating point number

Synopsis:

#include <math.h>

double scalbln ( double x,
                 long int n );

float scalblnf ( float x,
                 long int n );

long double scalblnl ( long double x,
                       long int n );

Arguments:

x
The floating point number that you want to multiply by the exponent.
n
The exponent to apply to the radix of the machine's floating-point arithmetic.

Library:

libm
The general-purpose math library.
libm-sve
(QNX Neutrino 7.1 or later) A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.

Description:

The scalbln(), scalblnf(), and scalblnl() functions compute x × rn, where r is the radix of the machine's floating-point arithmetic. The difference between the scalbn* and scalbln* functions is the type of the second argument.

To check for error situations, use feclearexcept() and fetestexcept(). For example:

Returns:

x × rn

If: These functions return: Errors:
x is NaN NaN
x is ±0.0 or ±Inf x
n is 0 x
The correct value would cause underflow The correct value, after rounding FE_UNDERFLOW
The correct value would cause overflow Inf FE_OVERFLOW

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.

Classification:

C11, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes