Difference between revisions of "cpp/numeric/math/fdim"
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| − | + | |family=fdim | |
| − | + | |param1=x | |
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| − | + | |constexpr_since=23 | |
| − | + | |desc=Returns the positive difference between {{c|x}} and {{c|y}}, that is, if {{c|x > y}}, returns {{c|x - y}}, otherwise (i.e. if {{c|1=x <= y}}) returns {{c|+0}}. | |
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===Parameters=== | ===Parameters=== | ||
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If the implementation supports IEEE floating-point arithmetic (IEC 60559), | If the implementation supports IEEE floating-point arithmetic (IEC 60559), | ||
| − | * If either argument is NaN, NaN is returned | + | * If either argument is NaN, NaN is returned. |
===Notes=== | ===Notes=== | ||
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int main() | int main() | ||
{ | { | ||
| − | std::cout << "fdim(4, 1) = " << std::fdim(4, 1) | + | std::cout << "fdim(4, 1) = " << std::fdim(4, 1) << '\n' |
| − | << " fdim(1, 4) = " << std::fdim(1, 4) << '\n' | + | << "fdim(1, 4) = " << std::fdim(1, 4) << '\n' |
| − | << "fdim(4,-1) = " << std::fdim(4, -1) | + | << "fdim(4,-1) = " << std::fdim(4, -1) << '\n' |
| − | << " fdim(1,-4) = " << std::fdim(1, -4) << '\n'; | + | << "fdim(1,-4) = " << std::fdim(1, -4) << '\n'; |
// error handling | // error handling | ||
| Line 84: | Line 64: | ||
} | } | ||
|output= | |output= | ||
| − | fdim(4, 1) = 3 fdim(1, 4) = 0 | + | fdim(4, 1) = 3 |
| − | fdim(4,-1) = 5 fdim(1,-4) = 5 | + | fdim(1, 4) = 0 |
| + | fdim(4,-1) = 5 | ||
| + | fdim(1,-4) = 5 | ||
fdim(1e308, -1e308) = inf | fdim(1e308, -1e308) = inf | ||
errno == ERANGE: Numerical result out of range | errno == ERANGE: Numerical result out of range | ||
Latest revision as of 09:22, 15 October 2023
| Defined in header <cmath>
|
||
| (1) | ||
float fdim ( float x, float y ); double fdim ( double x, double y ); |
(until C++23) | |
| constexpr /* floating-point-type */ fdim ( /* floating-point-type */ x, |
(since C++23) | |
| float fdimf( float x, float y ); |
(2) | (since C++11) (constexpr since C++23) |
| long double fdiml( long double x, long double y ); |
(3) | (since C++11) (constexpr since C++23) |
| Additional overloads (since C++11) |
||
| Defined in header <cmath>
|
||
| template< class Integer > double fdim ( Integer x, Integer y ); |
(A) | (constexpr since C++23) |
std::fdim for all cv-unqualified floating-point types as the type of the parameters.(since C++23)|
A) Additional overloads are provided for all integer types, which are treated as double.
|
(since C++11) |
Contents |
[edit] Parameters
| x, y | - | floating-point or integer values |
[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 math_errhandling.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
- If either argument is NaN, NaN is returned.
[edit] Notes
Equivalent to std::fmax(x - y, 0), except for the NaN handling requirements.
The additional overloads are not required to be provided exactly as (A). They only need to be sufficient to ensure that for their first argument num1 and second argument num2:
|
(until C++23) |
|
If num1 and num2 have arithmetic types, then std::fdim(num1, num2) has the same effect as std::fdim(static_cast</* common-floating-point-type */>(num1), If no such floating-point type with the greatest rank and subrank exists, then overload resolution does not result in a usable candidate from the overloads provided. |
(since C++23) |
[edit] Example
#include <cerrno> #include <cfenv> #include <cmath> #include <cstring> #include <iostream> #ifndef __GNUC__ #pragma STDC FENV_ACCESS ON #endif int main() { std::cout << "fdim(4, 1) = " << std::fdim(4, 1) << '\n' << "fdim(1, 4) = " << std::fdim(1, 4) << '\n' << "fdim(4,-1) = " << std::fdim(4, -1) << '\n' << "fdim(1,-4) = " << std::fdim(1, -4) << '\n'; // error handling errno = 0; std::feclearexcept(FE_ALL_EXCEPT); std::cout << "fdim(1e308, -1e308) = " << std::fdim(1e308, -1e308) << '\n'; if (errno == ERANGE) std::cout << " errno == ERANGE: " << std::strerror(errno) << '\n'; if (std::fetestexcept(FE_OVERFLOW)) std::cout << " FE_OVERFLOW raised\n"; }
Output:
fdim(4, 1) = 3
fdim(1, 4) = 0
fdim(4,-1) = 5
fdim(1,-4) = 5
fdim(1e308, -1e308) = inf
errno == ERANGE: Numerical result out of range
FE_OVERFLOW raised[edit] See also
| (C++11) |
computes absolute value of an integral value (|x|) (function) |
| (C++11)(C++11)(C++11) |
larger of two floating-point values (function) |
| C documentation for fdim
| |
