36 lines
1003 B
Plaintext
36 lines
1003 B
Plaintext
include "NSLog.incl"
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#define FB_M_E 2.7182818284590452
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double local fn StirlingGamma( x as double )
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return fn sqrt(2 * M_PI / x ) * fn pow(x / FB_M_E, x )
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end fn = 0.0
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double local fn LanczosGamma( x as double )
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int g = 7
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static double p(8) = {0.99999999999980993, 676.5203681218851, -1259.1392167224028,¬
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771.32342877765313, -176.61502916214059, 12.507343278686905, -0.13857109526572012,¬
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9.9843695780195716e-6, 1.5056327351493116e-7}
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if ( x < 0.5 ) then return M_PI / ( sin( M_PI * x ) * fn LanczosGamma( 1 - x ) )
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x -= 1.0
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double a = p(0)
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for int i = 1 to 8
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a += p(i) / ( x + i )
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next
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double t = x + g + 0.5
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return fn sqrt(2 * M_PI ) * fn pow(t, x + 0.5 ) * exp(-t ) * a
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end fn = 0.0
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void local fn RunGammaFunctions
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NSLog( @"Gamma\tStirling\t\t\t Lanczos" )
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for double i = 1.0 to 20
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double value = i / 10.0
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NSLog( @"%1.2f\t%17.15f\t %1.15f", value, fn StirlingGamma( value ), fn LanczosGamma( value ) )
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next
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end fn
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fn RunGammaFunctions
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HandleEvents
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