frexp

 

C

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Input/output support

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Thread support (C11)

Atomic operations (C11)

 

Numerics

Common mathematical functions

Floating-point environment

Complex number arithmetics

Random number generation

Type-generic math

 

Common mathematical functions

Functions
Basic operations
abslabsllabsimaxabs (C99) fabs divldivlldivimaxdiv (C99) fmod	remainder (C99) remquo (C99) fma (C99) fmax (C99) fmin (C99) fdim (C99) nannanfnanl (C99)(C99)(C99)
Exponential functions
exp exp2 (C99) expm1 (C99)	log log10 log1p (C99) log2 (C99)
Power functions
sqrt cbrt (C99)	hypot (C99) pow
Trigonometric and hyperbolic functions
sin cos tan asin acos atan atan2	sinh cosh tanh asinh (C99) acosh (C99) atanh (C99)
Error and gamma functions
erf (C99) erfc (C99)	lgamma (C99) tgamma (C99)
Nearest integer floating point operations
ceil floor roundlroundllround (C99)(C99)(C99)	trunc (C99) nearbyint (C99) rintlrintllrint (C99)(C99)(C99)
Floating point manipulation functions
ldexp scalbnscalbln (C99)(C99) ilogb (C99) logb (C99)	frexp modf nextafternexttoward (C99)(C99) copysign (C99)
Classification
fpclassify (C99)
isfinite (C99)
isinf (C99)
isnan (C99)
isnormal (C99)
signbit (C99)
Macro constants
HUGE_VALFHUGE_VALHUGE_VALL (C99)(C99)	FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C99)(C99)(C99)(C99)(C99)

 

Defined in header <math.h>
float       frexpf( float arg, int* exp );		(since C99)
double      frexp( double arg, int* exp );
long double frexpl( long double arg, int* exp );		(since C99)

Decomposes given floating point value arg to significand and exponent.

Parameters

arg	-	floating point value
exp	-	pointer to integer value to store the exponent to

Return value

Significand of the given floating point number in the range of [0.5; 1). The exponent is put into integer value pointed to by exp.

Example

Run this code

#include <stdio.h>
#include <math.h>
#include <float.h>
 
int main(void)
{
    int exp;
    printf("frexp(1.0,&exp)       = %+f * 2^", frexp(1.0,&exp));
    printf("(%+2d)\n", exp);
    printf("frexp(+0.0,&exp)      = %+f * 2^", frexp(+0.0,&exp));
    printf("(%+2d)\n", exp);
    printf("frexp(-0.0,&exp)      = %+f * 2^", frexp(-0.0,&exp));
    printf("(%+2d)\n", exp);
    printf("frexp(+INFINITY,&exp) = %+f * 2^", frexp(+INFINITY,&exp));
    printf("(%+2d)\n", exp);
    printf("frexp(-INFINITY,&exp) = %+f * 2^", frexp(-INFINITY,&exp));
    printf("(%+2d)\n", exp);
    printf("frexp(NAN,&exp)       = %+f * 2^", frexp(NAN,&exp));
    printf("(%+2d)\n", exp);
    printf("\n");
 
    printf("frexp(DBL_MIN,&exp) = %+f * 2^", frexp(DBL_MIN,&exp));
    printf("(%+2d)\n", exp);
    printf("frexp(DBL_MAX,&exp) = %+f * 2^", frexp(DBL_MAX,&exp));
    printf("(%+2d)\n", exp);
 
    return 0;
}

Possible output:

frexp(1.0,&exp)       = +0.500000 * 2^(+1)
frexp(+0.0,&exp)      = +0.000000 * 2^(+0)
frexp(-0.0,&exp)      = -0.000000 * 2^(+0)
frexp(+INFINITY,&exp) = +inf * 2^(+0)
frexp(-INFINITY,&exp) = -inf * 2^(+0)
frexp(NAN,&exp)       = +nan * 2^(+0)
 
frexp(DBL_MIN,&exp) = +0.500000 * 2^(-1021)
frexp(DBL_MAX,&exp) = +1.000000 * 2^(+1024)

See also

ldexpldexpfldexpl (C99)(C99)	multiplies a number by 2 raised to a power (function)
logblogbflogbl (C99)(C99)(C99)	extracts exponent of the given number (function)
ilogbilogbfilogbl (C99)(C99)(C99)	extracts exponent of the given number (function)
modfmodffmodfl (C99)(C99)	breaks a number into integer and fractional parts (function)
C++ documentation for frexp