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frexp(2) [plan9 man page]

FREXP(2)							System Calls Manual							  FREXP(2)

frexp, ldexp, modf - split into mantissa and exponent SYNOPSIS
#include <u.h> #include <libc.h> double frexp(double value, int *eptr) double ldexp(double value, int exp) double modf(double value, double *iptr) DESCRIPTION
Frexp returns the mantissa of value and stores the exponent indirectly through eptr, so that value = frexp(value)*2**(*eptr). Ldexp returns the quantity value*2**exp. Modf returns the positive fractional part of value and stores the integer part indirectly through iptr. SOURCE
/sys/src/libc/$objtype/frexp.c SEE ALSO
Ldexp returns 0 for underflow and the appropriately signed infinity for overflow. FREXP(2)

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FREXP(3)						     Linux Programmer's Manual							  FREXP(3)

frexp, frexpf, frexpl - convert floating-point number to fractional and integral components SYNOPSIS
#include <math.h> double frexp(double x, int *exp); float frexpf(float x, int *exp); long double frexpl(long double x, int *exp); Link with -lm. Feature Test Macro Requirements for glibc (see feature_test_macros(7)): frexpf(), frexpl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L; or cc -std=c99 DESCRIPTION
The frexp() function is used to split the number x into a normalized fraction and an exponent which is stored in exp. RETURN VALUE
The frexp() function returns the normalized fraction. If the argument x is not zero, the normalized fraction is x times a power of two, and its absolute value is always in the range 1/2 (inclusive) to 1 (exclusive), that is, [0.5,1). If x is zero, then the normalized fraction is zero and zero is stored in exp. If x is a NaN, a NaN is returned, and the value of *exp is unspecified. If x is positive infinity (negative infinity), positive infinity (negative infinity) is returned, and the value of *exp is unspecified. ERRORS
No errors occur. CONFORMING TO
C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD, C89. EXAMPLE
The program below produces results such as the following: $ ./a.out 2560 frexp(2560, &e) = 0.625: 0.625 * 2^12 = 2560 $ ./a.out -4 frexp(-4, &e) = -0.5: -0.5 * 2^3 = -4 Program source #include <math.h> #include <float.h> #include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { double x, r; int exp; x = strtod(argv[1], NULL); r = frexp(x, &exp); printf("frexp(%g, &e) = %g: %g * %d^%d = %g ", x, r, r, FLT_RADIX, exp, x); exit(EXIT_SUCCESS); } SEE ALSO
ldexp(3), modf(3) COLOPHON
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at 2010-09-20 FREXP(3)
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