Kahan summation: Difference between revisions
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(Kahan summation en FreeBASIC) |
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And this time, the compensated summation calculation comes out with one while the successive additions via a loop do not, as required. |
And this time, the compensated summation calculation comes out with one while the successive additions via a loop do not, as required. |
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=={{header|FreeBASIC}}== |
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<lang freebasic>Dim Shared As Double a, b, c |
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Function KahanSum (a As Double, b As Double, c As Double) As Double |
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Dim As Double sum = 0.0, i, y, t |
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c = 0.0 |
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For i = 1 To a |
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y = i - c |
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t = sum + y |
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c = (t - sum) - y |
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sum = t |
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Next i |
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Return sum |
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End Function |
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Function epsilon() As Double |
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Dim As Double eps = 1 |
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While (1 + eps <> 1) |
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eps /= 2 |
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Wend |
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Return eps |
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End Function |
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a = 1.0 |
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b = epsilon() |
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c = -b |
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Dim As Double s = (a + b) + c |
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Dim As Double k = KahanSum(a, b, c) |
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Dim As Double d = k - s |
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Print "Epsilon ="; b |
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Print "(a + b) + c ="; s |
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Print "Kahan sum ="; k |
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Print "Delta ="; d |
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Sleep</lang> |
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{{out}} |
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<pre> |
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Epsilon = 1.110223024625157e-016 |
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(a + b) + c = 0.9999999999999999 |
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Kahan sum = 1 |
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Delta = 1.110223024625157e-016 |
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</pre> |
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=={{header|Go}}== |
=={{header|Go}}== |
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