Dariusz Komosiński
6 years ago
committed by
GitHub
GitHub
11 changed files with 183 additions and 206 deletions
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// (c) Copyright Microsoft Corporation.
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// This source is subject to the Microsoft Public License (Ms-PL).
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// Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
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// All other rights reserved.
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using System; |
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namespace Avalonia.Controls.Utils |
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{ |
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internal static class DoubleUtil |
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{ |
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internal const double DBL_EPSILON = 1e-6; |
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/// <summary>
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/// AreClose - Returns whether or not two doubles are "close". That is, whether or
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/// not they are within epsilon of each other. Note that this epsilon is proportional
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/// to the numbers themselves to that AreClose survives scalar multiplication.
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/// There are plenty of ways for this to return false even for numbers which
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/// are theoretically identical, so no code calling this should fail to work if this
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/// returns false. This is important enough to repeat:
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/// NB: NO CODE CALLING THIS FUNCTION SHOULD DEPEND ON ACCURATE RESULTS - this should be
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/// used for optimizations *only*.
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/// </summary>
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/// <returns>
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/// bool - the result of the AreClose comparison.
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/// </returns>
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/// <param name="value1"> The first double to compare. </param>
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/// <param name="value2"> The second double to compare. </param>
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public static bool AreClose(double value1, double value2) |
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{ |
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//in case they are Infinities (then epsilon check does not work)
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if (value1 == value2) return true; |
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// This computes (|value1-value2| / (|value1| + |value2| + 10.0)) < DBL_EPSILON
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double eps = (Math.Abs(value1) + Math.Abs(value2) + 10.0) * DBL_EPSILON; |
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double delta = value1 - value2; |
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return (-eps < delta) && (eps > delta); |
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} |
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/// <summary>
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/// GreaterThan - Returns whether or not the first double is greater than the second double.
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/// That is, whether or not the first is strictly greater than *and* not within epsilon of
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/// the other number. Note that this epsilon is proportional to the numbers themselves
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/// to that AreClose survives scalar multiplication. Note,
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/// There are plenty of ways for this to return false even for numbers which
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/// are theoretically identical, so no code calling this should fail to work if this
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/// returns false. This is important enough to repeat:
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/// NB: NO CODE CALLING THIS FUNCTION SHOULD DEPEND ON ACCURATE RESULTS - this should be
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/// used for optimizations *only*.
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/// </summary>
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/// <returns>
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/// bool - the result of the GreaterThan comparison.
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/// </returns>
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/// <param name="value1"> The first double to compare. </param>
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/// <param name="value2"> The second double to compare. </param>
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public static bool GreaterThan(double value1, double value2) |
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{ |
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return (value1 > value2) && !AreClose(value1, value2); |
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} |
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/// <summary>
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/// GreaterThanOrClose - Returns whether or not the first double is greater than or close to
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/// the second double. That is, whether or not the first is strictly greater than or within
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/// epsilon of the other number. Note that this epsilon is proportional to the numbers
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/// themselves to that AreClose survives scalar multiplication. Note,
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/// There are plenty of ways for this to return false even for numbers which
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/// are theoretically identical, so no code calling this should fail to work if this
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/// returns false. This is important enough to repeat:
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/// NB: NO CODE CALLING THIS FUNCTION SHOULD DEPEND ON ACCURATE RESULTS - this should be
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/// used for optimizations *only*.
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/// </summary>
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/// <returns>
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/// bool - the result of the GreaterThanOrClose comparison.
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/// </returns>
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/// <param name="value1"> The first double to compare. </param>
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/// <param name="value2"> The second double to compare. </param>
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public static bool GreaterThanOrClose(double value1, double value2) |
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{ |
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return (value1 > value2) || AreClose(value1, value2); |
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} |
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/// <summary>
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/// IsZero - Returns whether or not the double is "close" to 0. Same as AreClose(double, 0),
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/// but this is faster.
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/// </summary>
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/// <returns>
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/// bool - the result of the IsZero comparison.
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/// </returns>
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/// <param name="value"> The double to compare to 0. </param>
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public static bool IsZero(double value) |
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{ |
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return Math.Abs(value) < 10.0 * DBL_EPSILON; |
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} |
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/// <summary>
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/// LessThan - Returns whether or not the first double is less than the second double.
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/// That is, whether or not the first is strictly less than *and* not within epsilon of
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/// the other number. Note that this epsilon is proportional to the numbers themselves
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/// to that AreClose survives scalar multiplication. Note,
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/// There are plenty of ways for this to return false even for numbers which
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/// are theoretically identical, so no code calling this should fail to work if this
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/// returns false. This is important enough to repeat:
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/// NB: NO CODE CALLING THIS FUNCTION SHOULD DEPEND ON ACCURATE RESULTS - this should be
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/// used for optimizations *only*.
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/// </summary>
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/// <returns>
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/// bool - the result of the LessThan comparison.
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/// </returns>
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/// <param name="value1"> The first double to compare. </param>
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/// <param name="value2"> The second double to compare. </param>
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public static bool LessThan(double value1, double value2) |
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{ |
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return (value1 < value2) && !AreClose(value1, value2); |
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} |
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/// <summary>
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/// LessThanOrClose - Returns whether or not the first double is less than or close to
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/// the second double. That is, whether or not the first is strictly less than or within
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/// epsilon of the other number. Note that this epsilon is proportional to the numbers
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/// themselves to that AreClose survives scalar multiplication. Note,
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/// There are plenty of ways for this to return false even for numbers which
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/// are theoretically identical, so no code calling this should fail to work if this
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/// returns false. This is important enough to repeat:
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/// NB: NO CODE CALLING THIS FUNCTION SHOULD DEPEND ON ACCURATE RESULTS - this should be
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/// used for optimizations *only*.
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/// </summary>
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/// <returns>
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/// bool - the result of the LessThanOrClose comparison.
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/// </returns>
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/// <param name="value1"> The first double to compare. </param>
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/// <param name="value2"> The second double to compare. </param>
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public static bool LessThanOrClose(double value1, double value2) |
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{ |
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return (value1 < value2) || AreClose(value1, value2); |
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} |
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} |
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} |
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