Math.IEEERemainder(Double, Double) Math.IEEERemainder(Double, Double) Math.IEEERemainder(Double, Double) Math.IEEERemainder(Double, Double) Method

Definition

Returns the remainder resulting from the division of a specified number by another specified number.

public:
 static double IEEERemainder(double x, double y);
public static double IEEERemainder (double x, double y);
static member IEEERemainder : double * double -> double
Public Shared Function IEEERemainder (x As Double, y As Double) As Double

Parameters

x
Double Double Double Double

A dividend.

y
Double Double Double Double

A divisor.

Returns

A number equal to x - (y Q), where Q is the quotient of x / y rounded to the nearest integer (if x / y falls halfway between two integers, the even integer is returned).

If x - (y Q) is zero, the value +0 is returned if x is positive, or -0 if x is negative.

If y = 0, NaN is returned.

Examples

The following example contrasts the remainder returned by the IEEERemainder method with the remainder returned by the remainder operator.

using System;

public class Example
{
   public static void Main()
   {
      Console.WriteLine($"{"IEEERemainder",35} {"Remainder operator",20}");
      ShowRemainders(3, 2);
      ShowRemainders(4, 2);
      ShowRemainders(10, 3);
      ShowRemainders(11, 3);
      ShowRemainders(27, 4);
      ShowRemainders(28, 5);
      ShowRemainders(17.8, 4);
      ShowRemainders(17.8, 4.1);
      ShowRemainders(-16.3, 4.1);
      ShowRemainders(17.8, -4.1);
      ShowRemainders(-17.8, -4.1);
   }

   private static void ShowRemainders(double number1, double number2)
   {
      var formula = $"{number1} / {number2} = ";
      var ieeeRemainder = Math.IEEERemainder(number1, number2);
      var remainder = number1 % number2;
      Console.WriteLine($"{formula,-16} {ieeeRemainder,18} {remainder,20}");
   }
}
// The example displays the following output:
//       
//
//                       IEEERemainder   Remainder operator
// 3 / 2 =                          -1                    1
// 4 / 2 =                           0                    0
// 10 / 3 =                          1                    1
// 11 / 3 =                         -1                    2
// 27 / 4 =                         -1                    3
// 28 / 5 =                         -2                    3
// 17.8 / 4 =                      1.8                  1.8
// 17.8 / 4.1 =                    1.4                  1.4
// -16.3 / 4.1 =    0.0999999999999979                   -4
// 17.8 / -4.1 =                   1.4                  1.4
// -17.8 / -4.1 =                 -1.4                 -1.4
Module Example
    Public Sub Main()
        Console.WriteLine($"{"IEEERemainder",35} {"Remainder operator",20}")
        ShowRemainders(3, 2)
        ShowRemainders(4, 2)
        ShowRemainders(10, 3)
        ShowRemainders(11, 3)
        ShowRemainders(27, 4)
        ShowRemainders(28, 5)
        ShowRemainders(17.8, 4)
        ShowRemainders(17.8, 4.1)
        ShowRemainders(-16.3, 4.1)
        ShowRemainders(17.8, -4.1)
        ShowRemainders(-17.8, -4.1)
    End Sub

    Private Sub ShowRemainders(number1 As Double, number2 As Double)
        Dim formula As String = $"{number1} / {number2} = "
        Dim ieeeRemainder As Double = Math.IEEERemainder(number1, number2)
        Dim remainder As Double = number1 Mod number2
        Console.WriteLine($"{formula,-16} {ieeeRemainder,18} {remainder,20}")
    End Sub
End Module
' The example displays the following output:
'       
'                       IEEERemainder   Remainder operator
' 3 / 2 =                          -1                    1
' 4 / 2 =                           0                    0
' 10 / 3 =                          1                    1
' 11 / 3 =                         -1                    2
' 27 / 4 =                         -1                    3
' 28 / 5 =                         -2                    3
' 17.8 / 4 =                      1.8                  1.8
' 17.8 / 4.1 =                    1.4                  1.4
' -16.3 / 4.1 =    0.0999999999999979                   -4
' 17.8 / -4.1 =                   1.4                  1.4
' -17.8 / -4.1 =                 -1.4                 -1.4

Remarks

This operation complies with the remainder operation defined in Section 5.1 of ANSI/IEEE Std 754-1985; IEEE Standard for Binary Floating-Point Arithmetic; Institute of Electrical and Electronics Engineers, Inc; 1985.

The IEEERemainder method is not the same as the remainder operator. Although both return the remainder after division, the formulas they use are different. The formula for the IEEERemainder method is:

IEEERemainder = dividend - (divisor * Math.Round(dividend / divisor))  

In contrast, the formula for the remainder operator is:

Remainder = (Math.Abs(dividend) - (Math.Abs(divisor) *   
            (Math.Floor(Math.Abs(dividend) / Math.Abs(divisor))))) *   
            Math.Sign(dividend)  

Applies to