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scalbln(3) Library Functions Manual scalbln(3)
scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl - multiply floating-point number by integral power of radix
Math library (libm, -lm)
#include <math.h> double scalbln(double x, long exp); float scalblnf(float x, long exp); long double scalblnl(long double x, long exp); double scalbn(double x, int exp); float scalbnf(float x, int exp); long double scalbnl(long double x, int exp); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): scalbln(), scalblnf(), scalblnl(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE scalbn(), scalbnf(), scalbnl(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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>.
On success, these functions return x * FLT_RADIX ** exp. If x is a NaN, a NaN is returned. If x is positive infinity (negative infinity), positive infinity (negative infinity) is returned. If x is +0 (-0), +0 (-0) 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.
See math_error(7) for information on how to determine whether an error has occurred when calling these functions. The following errors can occur: Range error, overflow An overflow floating-point exception (FE_OVERFLOW) is raised. Range error, underflow errno is set to ERANGE. An underflow floating-point exception (FE_UNDERFLOW) is raised.
For an explanation of the terms used in this section, see attributes(7). ┌─────────────────────────────────────┬───────────────┬─────────┐ │ Interface │ Attribute │ Value │ ├─────────────────────────────────────┼───────────────┼─────────┤ │ scalbn(), scalbnf(), scalbnl(), │ Thread safety │ MT-Safe │ │ scalbln(), scalblnf(), scalblnl() │ │ │ └─────────────────────────────────────┴───────────────┴─────────┘
C11, POSIX.1-2008.
glibc 2.1. C99, POSIX.1-2001.
These functions differ from the obsolete functions described in scalb(3) in the type of their second argument. The functions described on this page have a second argument of an integral type, while those in scalb(3) have a second argument of type double.
If FLT_RADIX equals 2 (which is usual), then scalbn() is equivalent to ldexp(3).
Before glibc 2.20, these functions did not set errno for range errors.
ldexp(3), scalb(3)
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Linux man-pages 6.9.1 2024-05-02 scalbln(3)
Pages that refer to this page: ldexp(3), scalb(3)