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37 lines
1.2 KiB
Fortran
37 lines
1.2 KiB
Fortran
*DECK DLGAMS
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SUBROUTINE DLGAMS (X, DLGAM, SGNGAM)
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C***BEGIN PROLOGUE DLGAMS
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C***PURPOSE Compute the logarithm of the absolute value of the Gamma
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C function.
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C***LIBRARY SLATEC (FNLIB)
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C***CATEGORY C7A
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C***TYPE DOUBLE PRECISION (ALGAMS-S, DLGAMS-D)
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C***KEYWORDS ABSOLUTE VALUE OF THE LOGARITHM OF THE GAMMA FUNCTION,
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C FNLIB, SPECIAL FUNCTIONS
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C***AUTHOR Fullerton, W., (LANL)
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C***DESCRIPTION
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C
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C DLGAMS(X,DLGAM,SGNGAM) calculates the double precision natural
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C logarithm of the absolute value of the Gamma function for
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C double precision argument X and stores the result in double
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C precision argument DLGAM.
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C
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C***REFERENCES (NONE)
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C***ROUTINES CALLED DLNGAM
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C***REVISION HISTORY (YYMMDD)
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C 770701 DATE WRITTEN
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C 890531 Changed all specific intrinsics to generic. (WRB)
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C 890531 REVISION DATE from Version 3.2
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C 891214 Prologue converted to Version 4.0 format. (BAB)
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C***END PROLOGUE DLGAMS
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DOUBLE PRECISION X, DLGAM, SGNGAM, DLNGAM
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C***FIRST EXECUTABLE STATEMENT DLGAMS
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DLGAM = DLNGAM(X)
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SGNGAM = 1.0D0
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IF (X.GT.0.D0) RETURN
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C
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INT = MOD (-AINT(X), 2.0D0) + 0.1D0
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IF (INT.EQ.0) SGNGAM = -1.0D0
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C
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RETURN
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END
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