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scalb(3) Library Functions Manual scalb(3)
scalb, scalbf, scalbl - multiply floating-point number by integral power of radix (OBSOLETE)
Math library (libm, -lm)
#include <math.h> [[deprecated]] double scalb(double x, double exp); [[deprecated]] float scalbf(float x, float exp); [[deprecated]] long double scalbl(long double x, long double exp); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): scalb(): _XOPEN_SOURCE >= 500 || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE scalbf(), scalbl(): _XOPEN_SOURCE >= 600 || /* 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 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.
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 errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised. Range error, overflow errno is set to ERANGE. 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 │ ├─────────────────────────────────────┼───────────────┼─────────┤ │ scalb(), scalbf(), scalbl() │ Thread safety │ MT-Safe │ └─────────────────────────────────────┴───────────────┴─────────┘
None.
scalb() 4.3BSD. Obsolescent in POSIX.1-2001; Removed in POSIX.1-2008, recommending the use of scalbln(3), scalblnf(3), or scalblnl(3) instead.
Before glibc 2.20, these functions did not set errno for domain and range errors.
ldexp(3), scalbln(3)
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Linux man-pages 6.9.1 2024-05-02 scalb(3)
Pages that refer to this page: scalbln(3), significand(3)