5 * Revision 1.1.1.2 1996/10/30 08:28:27 cernlib
8 * Revision 1.1.1.1 1996/04/12 15:29:22 plothow
12 #include "pdf/pilot.h"
14 C ..................................................................
19 C COMPUTES THE GAMMADO FUNCTION FOR A GIVEN ARGUMENT
22 C CALL GAMMADO(XX,GX,IER)
24 C DESCRIPTION OF PARAMETERS
25 C XX -THE ARGUMENT FOR THE GAMMADO FUNCTION
26 C GX -THE RESULTANT GAMMADO FUNCTION VALUE
27 C IER-RESULTANT ERROR CODE WHERE
29 C IER=1 XX IS WITHIN .000001 OF BEING A NEGATIVE INTEGER
30 C IER=2 XX GT 34.5, OVERFLOW, GX SET TO 1.0E38
35 C SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED
39 C THE RECURSION RELATION AND POLYNOMIAL APPROXIMATION
40 C BY C.HASTINGS,JR., 'APPROXIMATIONS FOR DIGITAL COMPUTERS',
41 C PRINCETON UNIVERSITY PRESS, 1955
43 C ..................................................................
45 SUBROUTINE GAMMADO(XX,GX,IER)
55 10 IF(X-2.0)110,110,15
59 50 IF(X-1.0)60,120,110
61 C SEE IF X IS NEAR NEGATIVE INTEGER OR ZERO
65 IF(ABS(Y)-ERR)130,130,64
66 64 IF(1.0-Y-ERR)130,130,70
68 C X NOT NEAR A NEGATIVE INTEGER OR ZERO
75 GY=1.0+Y*(-0.5771017+Y*(+0.9858540+Y*(-0.8764218+Y*(+0.8328212+
76 1Y*(-0.5684729+Y*(+0.2548205+Y*(-0.05149930)))))))