source: LMDZ6/trunk/libf/misc/ran1.f90 @ 5397

Last change on this file since 5397 was 5246, checked in by abarral, 7 weeks ago

Convert fixed-form to free-form sources .F -> .{f,F}90
(WIP: some .F remain, will be handled in subsequent commits)

  • Property copyright set to
    Name of program: LMDZ
    Creation date: 1984
    Version: LMDZ5
    License: CeCILL version 2
    Holder: Laboratoire de m\'et\'eorologie dynamique, CNRS, UMR 8539
    See the license file in the root directory
  • Property svn:eol-style set to native
  • Property svn:keywords set to Author Date Id Revision
File size: 881 bytes
Line 
1!
2! $Id: ran1.f90 5246 2024-10-21 12:58:45Z abarral $
3!
4FUNCTION RAN1(IDUM)
5  IMPLICIT NONE
6  REAL :: RAN1
7  REAL,SAVE :: R(97)
8  REAL,PARAMETER :: RM1=3.8580247E-6,RM2=7.4373773E-6
9  INTEGER,SAVE :: IFF=0
10  integer,save :: ix1,ix2,ix3
11  INTEGER,PARAMETER :: M1=259200,IA1=7141,IC1=54773
12  INTEGER,PARAMETER :: M2=134456,IA2=8121,IC2=28411
13  INTEGER,PARAMETER :: M3=243000,IA3=4561,IC3=51349
14  INTEGER :: IDUM,J
15
16  IF (IDUM.LT.0.OR.IFF.EQ.0) THEN
17    IFF=1
18    IX1=MOD(IC1-IDUM,M1)
19    IX1=MOD(IA1*IX1+IC1,M1)
20    IX2=MOD(IX1,M2)
21    IX1=MOD(IA1*IX1+IC1,M1)
22    IX3=MOD(IX1,M3)
23    DO J=1,97
24      IX1=MOD(IA1*IX1+IC1,M1)
25      IX2=MOD(IA2*IX2+IC2,M2)
26      R(J)=(REAL(IX1)+REAL(IX2)*RM2)*RM1
27    END DO
28    IDUM=1
29  ENDIF
30  IX1=MOD(IA1*IX1+IC1,M1)
31  IX2=MOD(IA2*IX2+IC2,M2)
32  IX3=MOD(IA3*IX3+IC3,M3)
33  J=1+(97*IX3)/M3
34  IF(J.GT.97.OR.J.LT.1) stop 1
35  RAN1=R(J)
36  R(J)=(REAL(IX1)+REAL(IX2)*RM2)*RM1
37  RETURN
38END FUNCTION RAN1
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