fabs, fabsf, fabsl, fabsd32, fabsd64, fabsd128
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) |
_Decimal32 fabsd32( _Decimal32 arg ); |
(4) | (since C23) |
_Decimal64 fabsd64( _Decimal64 arg ); |
(5) | (since C23) |
_Decimal128 fabsd128( _Decimal128 arg ); |
(6) | (since C23) |
Defined in header <tgmath.h> |
||
#define fabs( arith ) |
(7) | (since C99) |
1-6) Computes the absolute value of a floating point value
arg
.
The functions with decimal floating point parameters are declared if and only the implementation predefines |
(since C23) |
7) Type-generic macro: If the argument has type
_Decimal128
, _Decimal64
, _Decimal32
, (since C23)
long double
,
double
, or
float
,
fabsd128
, fabsd64
, fabsd32
, (since C23)
fabsl
,
fabs
, or
fabsf
is called, respectively. Otherwise, if the argument has integer type,
fabs
is called. Otherwise, if the argument is complex, then the macro invokes the corresponding complex function (
cabsf
,
cabs
,
cabsl
). Otherwise, the behavior is undefined.
Parameters
arg | - | floating point value |
arith | - | floating point or integer value |
Return value
If successful, returns the absolute value of arg
(\(\small |arg| \)|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
#include <stdio.h> #include <math.h> #define PI 3.14159 /* This numerical integration assumes all area is positive. */ double integrate(double a, double b, /* assume a < b */ double f(double), unsigned steps) { /* assume steps > 0 */ const double dx = (b-a)/steps; double sum = 0.0; for (double x = a; x < b; x += dx) sum += fabs(f(x)); return dx*sum; } 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)); printf("%f\n", integrate(-PI,+PI,sin,10*1000)); }
Output:
fabs(+3) = 3.000000 fabs(-3) = 3.000000 fabs(-0) = 0.000000 fabs(-Inf) = inf 4.000000
References
- C17 standard (ISO/IEC 9899:2018):
- 7.12.7.2 The fabs functions (p: 181)
- 7.25 Type-generic math <tgmath.h> (p: 272-273)
- F.10.4.2 The fabs functions (p: 382)
- C11 standard (ISO/IEC 9899:2011):
- 7.12.7.2 The fabs functions (p: 248)
- 7.25 Type-generic math <tgmath.h> (p: 373-375)
- F.10.4.2 The fabs functions (p: 524)
- C99 standard (ISO/IEC 9899:1999):
- 7.12.7.2 The fabs functions (p: 228-229)
- 7.22 Type-generic math <tgmath.h> (p: 335-337)
- F.9.4.2 The fabs functions (p: 460)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.5.6.2 The fabs function
See also
(C99)
|
computes absolute value of an integral value (\(\small{|x|}\)|x|) (function) |
(C99)(C99)(C99)
|
produces a value with the magnitude of a given value and the sign of another given value (function) |
(C99)
|
checks if the given number is negative (function macro) |
(C99)(C99)(C99)
|
computes the magnitude of a complex number (function) |
C++ documentation for fabs |
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