33 lines
1.4 KiB
C#
33 lines
1.4 KiB
C#
namespace Just.PreciseMath.Tests;
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public class PreciseMathTests
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{
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[Fact]
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public void AbsPreservesBothComponentsAndCanonicalSpecialValues()
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{
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double[] scalars = [0.0, -0.0, 1.0, -1.0, double.Epsilon, -double.Epsilon,
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double.MaxValue, double.MinValue, double.PositiveInfinity, double.NegativeInfinity, double.NaN];
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foreach (double scalar in scalars)
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{
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// Binary64 is an independent reference when the input has no residual.
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DoubleDouble actual = DDMath.Abs(new DoubleDouble(scalar));
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AssertBits(actual, double.IsNaN(scalar) ? double.NaN : Math.Abs(scalar), 0.0);
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DoubleDouble.IsCanonical(actual).ShouldBeTrue();
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}
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foreach (double low in new[] { Math.ScaleB(1.0, -54), -Math.ScaleB(1.0, -54), double.Epsilon, -double.Epsilon })
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{
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DoubleDouble positive = DoubleDouble.FromComponents(1.0, low);
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DoubleDouble negative = DoubleDouble.FromComponents(-1.0, -low);
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AssertBits(DDMath.Abs(positive), 1.0, low);
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AssertBits(DDMath.Abs(negative), 1.0, low);
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}
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}
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private static void AssertBits(DoubleDouble actual, double high, double low)
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{
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BitConverter.DoubleToInt64Bits(actual.High).ShouldBe(BitConverter.DoubleToInt64Bits(high));
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BitConverter.DoubleToInt64Bits(actual.Low).ShouldBe(BitConverter.DoubleToInt64Bits(low));
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}
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}
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