std::remainder,std::remainderf,std::remainderl (3) - Linux Manuals

std::remainder,std::remainderf,std::remainderl: std::remainder,std::remainderf,std::remainderl

NAME

std::remainder,std::remainderf,std::remainderl - std::remainder,std::remainderf,std::remainderl

Synopsis

Defined in header <cmath>
float remainder ( float x, float y ); (1) (since C++11)
float remainderf( float x, float y );
double remainder ( double x, double y ); (2) (since C++11)
long double remainder ( long double x, long double y ); (3) (since C++11)
long double remainderl( long double x, long double y );
Promoted remainder ( Arithmetic1 x, Arithmetic2 y ); (4) (since C++11)

1-3) Computes the IEEE remainder of the floating point division operation x/y.
4) A set of overloads or a function template for all combinations of arguments of arithmetic_type not covered by (1-3). If any argument has integral_type, it is cast to double. If any other argument is long double, then the return type is long double, otherwise it is double.
The IEEE floating-point remainder of the division operation x/y calculated by this function is exactly the value x - n*y, where the value n is the integral value nearest the exact value x/y. When |n-x/y| = ½, the value n is chosen to be even.
In contrast to std::fmod(), the returned value is not guaranteed to have the same sign as x.
If the returned value is 0, it will have the same sign as x.

Parameters

x, y - values of floating-point or integral_types

Return value

If successful, returns the IEEE floating-point remainder of the division x/y as defined above.
If a domain error occurs, an implementation-defined value is returned (NaN where supported)
If a range error occurs due to underflow, the correct result is returned.
If y is zero, but the domain error does not occur, zero is returned.

Error handling

Errors are reported as specified in math_errhandling.
Domain error may occur if y is zero.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),

* The current rounding_mode has no effect.
* FE_INEXACT is never raised, the result is always exact.
* If x is ±∞ and y is not NaN, NaN is returned and FE_INVALID is raised
* If y is ±0 and x is not NaN, NaN is returned and FE_INVALID is raised
* If either argument is NaN, NaN is returned

Notes

POSIX_requires that a domain error occurs if x is infinite or y is zero.
std::fmod, but not std::remainder is useful for doing silent wrapping of floating-point types to unsigned integer types: (0.0 <= (y = std::fmod( std::rint(x), 65536.0 )) ? y : 65536.0 + y) is in the range [-0.0 .. 65535.0], which corresponds to unsigned short, but std::remainder(std::rint(x), 65536.0) is in the range [-32767.0, +32768.0], which is outside of the range of signed short.

Example

// Run this code

  #include <iostream>
  #include <cmath>
  #include <cfenv>

  #pragma STDC FENV_ACCESS ON
  int main()
  {
      std::cout << "remainder(+5.1, +3.0) = " << std::remainder(5.1,3) << '\n'
                << "remainder(-5.1, +3.0) = " << std::remainder(-5.1,3) << '\n'
                << "remainder(+5.1, -3.0) = " << std::remainder(5.1,-3) << '\n'
                << "remainder(-5.1, -3.0) = " << std::remainder(-5.1,-3) << '\n';

      // special values
      std::cout << "remainder(-0.0, 1.0) = " << std::remainder(-0.0, 1) << '\n'
                << "remainder(5.1, Inf) = " << std::remainder(5.1, INFINITY) << '\n';

      // error handling
      std::feclearexcept(FE_ALL_EXCEPT);
      std::cout << "remainder(+5.1, 0) = " << std::remainder(5.1, 0) << '\n';
      if(fetestexcept(FE_INVALID))
          std::cout << " FE_INVALID raised\n";
  }

Possible output:

  remainder(+5.1, +3.0) = -0.9
  remainder(-5.1, +3.0) = 0.9
  remainder(+5.1, -3.0) = -0.9
  remainder(-5.1, -3.0) = 0.9
  remainder(-0.0, 1.0) = -0
  remainder(5.1, Inf) = 5.1
  remainder(+5.1, 0) = -nan
      FE_INVALID raised