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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
/*============================================================
**
** Purpose: Some single-precision floating-point math operations
**
===========================================================*/
//This class contains only static members and doesn't require serialization.
using System.Runtime;
using System.Runtime.CompilerServices;
namespace System
{
public static partial class MathF
{
public const float E = 2.71828183f;
public const float PI = 3.14159265f;
private const int maxRoundingDigits = 6;
// This table is required for the Round function which can specify the number of digits to round to
private static float[] roundPower10Single = new float[] {
1e0f, 1e1f, 1e2f, 1e3f, 1e4f, 1e5f, 1e6f
};
private static float singleRoundLimit = 1e8f;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static float Abs(float x)
{
return Math.Abs(x);
}
public static float IEEERemainder(float x, float y)
{
if (float.IsNaN(x))
{
return x; // IEEE 754-2008: NaN payload must be preserved
}
if (float.IsNaN(y))
{
return y; // IEEE 754-2008: NaN payload must be preserved
}
var regularMod = x % y;
if (float.IsNaN(regularMod))
{
return float.NaN;
}
if ((regularMod == 0) && float.IsNegative(x))
{
return float.NegativeZero;
}
var alternativeResult = (regularMod - (Abs(y) * Sign(x)));
if (Abs(alternativeResult) == Abs(regularMod))
{
var divisionResult = x / y;
var roundedResult = Round(divisionResult);
if (Abs(roundedResult) > Abs(divisionResult))
{
return alternativeResult;
}
else
{
return regularMod;
}
}
if (Abs(alternativeResult) < Abs(regularMod))
{
return alternativeResult;
}
else
{
return regularMod;
}
}
public static float Log(float x, float y)
{
if (float.IsNaN(x))
{
return x; // IEEE 754-2008: NaN payload must be preserved
}
if (float.IsNaN(y))
{
return y; // IEEE 754-2008: NaN payload must be preserved
}
if (y == 1)
{
return float.NaN;
}
if ((x != 1) && ((y == 0) || float.IsPositiveInfinity(y)))
{
return float.NaN;
}
return Log(x) / Log(y);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static float Max(float x, float y)
{
return Math.Max(x, y);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static float Min(float x, float y)
{
return Math.Min(x, y);
}
[Intrinsic]
public static float Round(float x)
{
// ************************************************************************************
// IMPORTANT: Do not change this implementation without also updating Math.Round(double),
// FloatingPointUtils::round(double), and FloatingPointUtils::round(float)
// ************************************************************************************
// If the number has no fractional part do nothing
// This shortcut is necessary to workaround precision loss in borderline cases on some platforms
if (x == (float)((int)x))
{
return x;
}
// We had a number that was equally close to 2 integers.
// We need to return the even one.
float flrTempVal = Floor(x + 0.5f);
if ((x == (Floor(x) + 0.5f)) && (FMod(flrTempVal, 2.0f) != 0))
{
flrTempVal -= 1.0f;
}
return CopySign(flrTempVal, x);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static float Round(float x, int digits)
{
return Round(x, digits, MidpointRounding.ToEven);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static float Round(float x, MidpointRounding mode)
{
return Round(x, 0, mode);
}
public static unsafe float Round(float x, int digits, MidpointRounding mode)
{
if ((digits < 0) || (digits > maxRoundingDigits))
{
throw new ArgumentOutOfRangeException(nameof(digits), SR.ArgumentOutOfRange_RoundingDigits);
}
if (mode < MidpointRounding.ToEven || mode > MidpointRounding.AwayFromZero)
{
throw new ArgumentException(SR.Format(SR.Argument_InvalidEnum, mode, nameof(MidpointRounding)), nameof(mode));
}
if (Abs(x) < singleRoundLimit)
{
var power10 = roundPower10Single[digits];
x *= power10;
if (mode == MidpointRounding.AwayFromZero)
{
var fraction = ModF(x, &x);
if (Abs(fraction) >= 0.5f)
{
x += Sign(fraction);
}
}
else
{
x = Round(x);
}
x /= power10;
}
return x;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static int Sign(float x)
{
return Math.Sign(x);
}
public static unsafe float Truncate(float x)
{
ModF(x, &x);
return x;
}
private static unsafe float CopySign(float x, float y)
{
var xbits = BitConverter.SingleToInt32Bits(x);
var ybits = BitConverter.SingleToInt32Bits(y);
// If the sign bits of x and y are not the same,
// flip the sign bit of x and return the new value;
// otherwise, just return x
if (((xbits ^ ybits) >> 31) != 0)
{
return BitConverter.Int32BitsToSingle(xbits ^ int.MinValue);
}
return x;
}
}
}
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