fdim, fdimf, fdiml
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Defined in header
<math.h>
float fdimf( float x, float y );
(1)
(since C99)
double fdim( double x, double y );
(2)
(since C99)
long double fdiml( long double x, long double y );
(3)
(since C99)
Defined in header
<tgmath.h>
#define fdim( x, y )
(4)
(since C99)
1-3) Returns the positive difference between x and y, that is, if x>y, returns x-y, otherwise (if x≤y), returns +0.
4) Type-generic macro: If any argument has type long double,
fdiml is called. Otherwise, if any argument has integer type or has type double, fdim is called. Otherwise, fdimf is called.[edit] Parameters
x, y
-
floating-point value
[edit] Return value
If successful, returns the positive difference between x and y.
If a range error due to overflow occurs, +HUGE_VAL , +HUGE_VALF, or +HUGE_VALL is returned.
If a range error due to underflow occurs, the correct value (after rounding) is returned.
[edit] Error handling
Errors are reported as specified in Template:rllpt.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
- If either argument is NaN, NaN is returned.
[edit] Notes
Equivalent to fmax (x-y, 0) except for the NaN handling requirements.
[edit] Example
Run this code
#include <errno.h> #include <fenv.h> #include <math.h> #include <stdio.h> // #pragma STDC FENV_ACCESS ON int main(void) { printf ("fdim(4, 1) = %f, fdim(1, 4)=%f\n", fdim(4,1), fdim(1,4)); printf ("fdim(4,-1) = %f, fdim(1,-4)=%f\n", fdim(4,-1), fdim(1,-4)); //error handling errno = 0; feclearexcept (FE_ALL_EXCEPT ); printf ("fdim(1e308, -1e308) = %f\n", fdim(1e308, -1e308)); if (errno == ERANGE ) perror (" errno == ERANGE"); if (fetestexcept (FE_OVERFLOW )) puts (" FE_OVERFLOW raised"); }
Possible output:
fdim(4, 1) = 3.000000, fdim(1, 4)=0.000000 fdim(4,-1) = 5.000000, fdim(1,-4)=5.000000 fdim(1e308, -1e308) = inf errno == ERANGE: Numerical result out of range FE_OVERFLOW raised
[edit] References
- C23 standard (ISO/IEC 9899:2024):
- 7.12.12.1 The fdim functions (p: TBD)
- 7.25 Type-generic math <tgmath.h> (p: TBD)
- F.10.9.1 The fdim functions (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.12.12.1 The fdim functions (p: 187-188)
- 7.25 Type-generic math <tgmath.h> (p: 272-273)
- F.10.9.1 The fdim functions (p: 386)
- C11 standard (ISO/IEC 9899:2011):
- 7.12.12.1 The fdim functions (p: 257)
- 7.25 Type-generic math <tgmath.h> (p: 373-375)
- F.10.9.1 The fdim functions (p: 530)
- C99 standard (ISO/IEC 9899:1999):
- 7.12.12.1 The fdim functions (p: 238)
- 7.22 Type-generic math <tgmath.h> (p: 335-337)
- F.9.9.1 The fdim functions (p: 466)
[edit] See also
C++ documentation for fdim