fdim
From cppreference.com
| Defined in header <math.h>
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| 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>
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| #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.Parameters
| x, y | - | floating point value |
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.
Error handling
Errors are reported as specified in math_errhandling.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
- If either argument is NaN, NaN is returned
Notes
Equivalent to fmax(x-y, 0) except for the NaN handling requirements.
Example
Run this code
#include <stdio.h> #include <math.h> #include <errno.h> #include <fenv.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 raisedReferences
- 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)
See also
| (C99) |
computes absolute value of an integral value (|x|) (function) |
| (C99)(C99)(C99) |
determines larger of two floating-point values (function) |
| C++ documentation for fdim
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