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ldexp(3) [osx man page]

LDEXP(3)						   BSD Library Functions Manual 						  LDEXP(3)

ldexp -- multiply by integer power of 2 SYNOPSIS
#include <math.h> double ldexp(double x, int n); long double ldexpl(long double x, int n); float ldexpf(float x, int n); DESCRIPTION
The ldexp() functions multiply x by 2 to the power n. SPECIAL VALUES
ldexp(+-0, n) returns +-0. ldexp(x, 0) returns x. ldexp(+-infinity, n) returns +-infinity. SEE ALSO
math(3), scalbn(3) STANDARDS
The ldexp() functions conform to ISO/IEC 9899:2011. BSD
December 11, 2006 BSD

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frexp(3)						     Library Functions Manual							  frexp(3)

frexp, ldexp, logb, scalb - Manipulate floating-point numbers LIBRARY
Math Library (libm.a) SYNOPSIS
#include <math.h> double frexp (double x, int *n); float frexpf (float x, int *n); long double frexpl (long double x, int *n); double ldexp (double y, int n); float ldexpf (float y, int n); long double ldexpl (long double y, int n); double logb (double x); float logbf (float x); long double logbl (long double x); double scalb (double x, double n); float scalbf (float x, float n); long double scalbl (long dou- ble x, long double n); STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: frexp(): XPG4 ldexp(): XPG4 logb(): XPG4-UNIX scalb(): XPG4-UNIX Refer to the standards(5) reference page for more information about industry standards and associated tags. DESCRIPTION
Every nonzero number can be written uniquely as the normalized mantissa (fraction) z times 2 raised to the power p, where the absolute value of z is in the range [0.5, 1.0), and the exponent p, is an integer. The frexp(), frexpf(), and frexpl() functions break a floating-point number into a normalized fraction and an integral power of 2. The functions store the integer in the int object pointed to by the n parameter and return the fraction part. The ldexp(), ldexpf(), and ldexpl() functions multiply a floating-point number, y, by an integral power of 2. The logb(), logbf(), and logbl() functions return a signed integer converted to double-precision floating-point and so chosen that 1 <= |x|/2**n < 2 unless x = 0 or |x| = infinity or x lies between 0 and the Underflow Threshold. IEEE 754 defines logb(+infinity) = +infinity and logb(0) = -infinity. The latter is required to signal Division-by-Zero. The scalb(), scalbf(), and scalbl() functions are defined as x*(2**n) for integer n. The following table describes function behavior in response to exceptional arguments: ---------------------------------------------------------------------- Function Exceptional Argument Routine Behavior ---------------------------------------------------------------------- frexp(), frexpf(), frexpl() |x| = infinity Invalid argument logb(), logbf(), logbl() |x| = infinity Invalid argument scalb(), scalbf(), scalbl() x*(2**n) > max_float Overflow scalb(), scalbf(), scalbl() x*(2**n) < min_float Underflow ldexp(), ldexpf(), ldexpl() x*(2**n) > max_float Overflow ldexp(), ldexpf(), ldexpl() x*(2**n) < min_float Underflow ---------------------------------------------------------------------- The following table lists boundary values used by these functions: -------------------------------------------------------------------- Value Name Data Type Hexadecimal Value Decimal Value -------------------------------------------------------------------- max_float S_FLOAT 7F7FFFFF 3.402823e38 T_FLOAT 7FEFFFFFFFFFFFFF 1.797693134862316e308 min_float S_FLOAT 00000001 1.4012985e-45 T_FLOAT 0000000000000001 4.940656458412465e-324 -------------------------------------------------------------------- delim off frexp(3)
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