source:
PSPA/parmelaPSPA/trunk/gser.f
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430
Last change on this file since 430 was 12, checked in by , 12 years ago | |
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1 | SUBROUTINE GSER(GAMSER,A,X,GLN) |
2 | PARAMETER (ITMAX=100,EPS=3.E-7) |
3 | GLN=GAMMLN(A) |
4 | IF(X.LE.0.)THEN |
5 | IF(X.LT.0.)PAUSE |
6 | GAMSER=0. |
7 | RETURN |
8 | ENDIF |
9 | AP=A |
10 | SUM=1./A |
11 | DEL=SUM |
12 | DO 11 N=1,ITMAX |
13 | AP=AP+1. |
14 | DEL=DEL*X/AP |
15 | SUM=SUM+DEL |
16 | IF(ABS(DEL).LT.ABS(SUM)*EPS)GO TO 1 |
17 | 11 CONTINUE |
18 | PAUSE 'A TOO LARGE, ITMAX TOO SMALL' |
19 | 1 GAMSER=SUM*EXP(-X+A*LOG(X)-GLN) |
20 | RETURN |
21 | END |
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