36 lines
836 B
Text
36 lines
836 B
Text
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' Gamma function
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DECLARE FUNCTION Gamma# (Z#)
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DECLARE FUNCTION LnGamma# (BYVAL Z#)
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FOR X# = .1 TO 2.05 STEP .1
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PRINT USING "##.# "; X#;
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PRINT USING "#.#########"; Gamma#(X#)
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NEXT X#
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END
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FUNCTION Gamma# (Z#)
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Gamma# = EXP(LnGamma#(Z#))
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END FUNCTION
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FUNCTION LnGamma# (BYVAL Z#)
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CONST PI# = 3.14159265358979#
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DIM LZ#(6)
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LZ#(0) = 1.00000000019001#
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LZ#(1) = 76.1800917294715#
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LZ#(2) = -86.5053203294168#
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LZ#(3) = 24.0140982408309#
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LZ#(4) = -1.23173957245015#
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LZ#(5) = 1.2086509738662D-03
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LZ#(6) = -.000005395239385#
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IF Z# < .5 THEN
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LnGamma# = LOG(PI# / SIN(PI# * Z#)) - LnGamma#(1# - Z#)
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ELSE
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Z# = Z# - 1#
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B# = Z# + 5.5
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A# = LZ#(0)
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FOR I% = 1 TO 6
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A# = A# + LZ#(I%) / (Z# + I%)
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NEXT I%
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LnGamma# = (LOG(SQR(2 * PI#)) + LOG(A#) - B#) + LOG(B#) * (Z# + .5)
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END IF
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END FUNCTION
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