Statistics/Chi-squared distribution: Difference between revisions
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→{{header|Python}}: gamma
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m (→{{header|Python}}: gamma) |
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Line 302:
from math import
from matplotlib.pyplot import plot, legend, ylim
def gamma(x):
''' gamma function, accurate to about 12 decimal places '''
p = [0.99999999999980993, 676.5203681218851, -1259.1392167224028,
771.32342877765313, -176.61502916214059, 12.507343278686905,
-0.13857109526572012, 9.9843695780195716e-6, 1.5056327351493116e-7]
if x < 0.5:
return pi / (sin(pi * x) * gamma(1.0 - x))
x -= 1.0
t = p[0]
for i in range(1, 9):
t += p[i] / (x + i)
w = x + 7.5
return sqrt(2.0 * pi) * w**(x+0.5) * exp(-w) * t
def χ2(x, k):
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