diff --git a/src/Numerics/Interpolation/CubicSpline.cs b/src/Numerics/Interpolation/CubicSpline.cs index d2344901..0500c37e 100644 --- a/src/Numerics/Interpolation/CubicSpline.cs +++ b/src/Numerics/Interpolation/CubicSpline.cs @@ -237,7 +237,6 @@ namespace MathNet.Numerics.Interpolation var dd = new double[x.Length]; var hPrev = x[1] - x[0]; - // This check is quite costly as it usually involves a Math.Pow(). var mPrevIs0 = m[0].AlmostEqual(0.0); for (var i = 1; i < x.Length - 1; ++i) diff --git a/src/Numerics/Precision.Equality.cs b/src/Numerics/Precision.Equality.cs index 8f4af6cc..4d64bd41 100644 --- a/src/Numerics/Precision.Equality.cs +++ b/src/Numerics/Precision.Equality.cs @@ -34,8 +34,6 @@ using Complex = System.Numerics.Complex; namespace MathNet.Numerics { - // TODO PERF: Cache/Precompute 10^x terms - public static partial class Precision { /// @@ -355,7 +353,7 @@ namespace MathNet.Numerics // 10^(-numberOfDecimalPlaces). We divide by two so that we have half the range // on each side of the numbers, e.g. if decimalPlaces == 2, // then 0.01 will equal between 0.005 and 0.015, but not 0.02 and not 0.00 - return Math.Abs(diff) < Math.Pow(10, -decimalPlaces) / 2d; + return Math.Abs(diff) < Pow10(-decimalPlaces) * 0.5; } /// @@ -431,7 +429,7 @@ namespace MathNet.Numerics // 10^(-numberOfDecimalPlaces). We divide by two so that we have half the range // on each side of the numbers, e.g. if decimalPlaces == 2, // then 0.01 will equal between 0.005 and 0.015, but not 0.02 and not 0.00 - return Math.Abs(diff) < Math.Pow(10, -decimalPlaces) / 2d; + return Math.Abs(diff) < Pow10(-decimalPlaces) * 0.5; } // If the magnitudes of the two numbers are equal to within one magnitude the numbers could potentially be equal @@ -447,7 +445,7 @@ namespace MathNet.Numerics // 10^(-numberOfDecimalPlaces). We divide by two so that we have half the range // on each side of the numbers, e.g. if decimalPlaces == 2, // then 0.01 will equal between 0.00995 and 0.01005, but not 0.0015 and not 0.0095 - return Math.Abs(diff) < Math.Pow(10, magnitudeOfMax - decimalPlaces) / 2d; + return Math.Abs(diff) < Pow10(magnitudeOfMax - decimalPlaces) * 0.5; } /// @@ -1041,5 +1039,19 @@ namespace MathNet.Numerics { return AlmostEqualNormRelative(a.L2Norm(), b.L2Norm(), (a - b).L2Norm(), decimalPlaces); } + + private static readonly double[] NegativePowersOf10 = new double[] + { + 1, 0.1, 0.01, 1e-3, 1e-4, 1e-5, 1e-6, 1e-7, 1e-8, 1e-9, + 1e-10, 1e-11, 1e-12, 1e-13, 1e-14, 1e-15, 1e-16, + 1e-17, 1e-18, 1e-19, 1e-20 + }; + + private static double Pow10(int y) + { + return -NegativePowersOf10.Length < y && y <= 0 + ? NegativePowersOf10[-y] + : Math.Pow(10.0, y); + } } }