fabs, fabsf, fabsl

 

C

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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       fabsf( float arg );	(1)	(since C99)
double      fabs( double arg );	(2)
long double fabsl( long double arg );	(3)	(since C99)
Defined in header <tgmath.h>
#define fabs( arg )	(4)	(since C99)

1-3) Computes the absolute value of a floating point value arg.

4) Type-generic macro: If the argument has type long double, fabsl is called. Otherwise, if the argument has integer type or has type double, fabs is called. Otherwise, fabsf is called. If the argument is complex, then the macro invokes the corresponding complex function (cabsf, cabs, cabsl)

Parameters

arg

-

floating point value

Return value

If successful, returns the absolute value of arg (|arg|). The value returned is exact and does not depend on any rounding modes.

Error handling

This function is not subject to any of the error conditions specified in math_errhandling

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

• If the argument is ±0, +0 is returned
• If the argument is ±∞, +∞ is returned
• If the argument is NaN, NaN is returned

Example

Run this code

#include <stdio.h>
#include <math.h>
 
int main(void)
{
    printf("fabs(+3) = %f\n", fabs(+3.0));
    printf("fabs(-3) = %f\n", fabs(-3.0));
    // special values
    printf("fabs(-0) = %f\n", fabs(-0.0));
    printf("fabs(-Inf) = %f\n", fabs(-INFINITY));
}

Output:

fabs(+3) = 3.000000
fabs(-3) = 3.000000
fabs(-0) = 0.000000
fabs(-Inf) = inf

See also

abslabsllabs (C99)	computes absolute value of an integral value (|x|) (function)
copysigncopysignfcopysignl (C99)(C99)(C99)	produces a value with the magnitude of a given value and the sign of another given value (function)
signbit (C99)	checks if the given number is negative (function)
cabscabsfcabsl (C99)(C99)(C99)	computes the magnitude of a complex number (function)
C++ documentation for fabs