SCALBN(3)

SCALBN(3) | Library Functions Manual | SCALBN(3)

# NAME

`scalbn`, `scalbnf`, `scalbnl` —
exponent using FLT_RADIX

# LIBRARY

Math Library (libm, -lm)

# SYNOPSIS

`#include <math.h>`

double
`scalbn`(double x, int n);

float
`scalbnf`(float x, int n);

long double
`scalbnl`(long double x, int n);

# DESCRIPTION

The `scalbn`(), `scalbnf`(), and `scalbnl`() functions compute x * r^n, where r is the radix of the machine's floating point arithmetic, defined by the `FLT_RADIX` constant in `<float.h>`. The rationale is efficiency; r^n is not computed explicitly.

# RETURN VALUES

As described above, upon successful completion, the described functions return the exponent computed using `FLT_RADIX`. Otherwise the following may occur:

1. When the result would cause an overflow, a range error occurs and `±HUGE_VAL`, `±HUGE_VALF`, or `±HUGE_VALL` is returned according to the sign of x and the return type of the corresponding function.
2. When the correct value would cause an underflow and it is not representable, a range error occurs and either 0.0 or an implementation-defined value is returned. When an underflow occurs but the correct value is representable, a range error occurs but the correct value is returned.
3. If x is ±0 or ±Inf, x is returned. Likewise, if n is zero, x is returned. If x is NaN, NaN is returned.

# SEE ALSO

exp(3), frexp(3), ldexp(3), math(3)

# STANDARDS

The described functions conform to ISO/IEC 9899:1999 (“ISO C99”).

September 18, 2011 | NetBSD 9.0