source: trunk/LMDZ.VENUS/libf/phyvenus/dtridgl.F @ 3556

Last change on this file since 3556 was 2560, checked in by slebonnois, 3 years ago

SL: Implementation of SW computation based on generic model. Switch between this new SW module or old module that reads R. Haus tables implemented with a key (solarchoice)

File size: 907 bytes
Line 
1      SUBROUTINE DTRIDGL(L,AF,BF,CF,DF,XK)
2
3C  GCM2.0  Feb 2003
4
5C     DOUBLE PRECISION VERSION OF TRIDGL
6
7!!      PARAMETER (NMAX=201)
8      IMPLICIT REAL*8  (A-H,O-Z)
9      DIMENSION AF(L),BF(L),CF(L),DF(L),XK(L)
10      DIMENSION AS(2*L),DS(2*L)
11
12C*    THIS SUBROUTINE SOLVES A SYSTEM OF TRIDIAGIONAL MATRIX
13C*    EQUATIONS. THE FORM OF THE EQUATIONS ARE:
14C*    A(I)*X(I-1) + B(I)*X(I) + C(I)*X(I+1) = D(I)
15C*    WHERE I=1,L  LESS THAN 103.
16C* ..............REVIEWED -CP........
17
18C======================================================================C
19
20      AS(L) = AF(L)/BF(L)
21      DS(L) = DF(L)/BF(L)
22
23      DO I=2,L
24        X         = 1./(BF(L+1-I) - CF(L+1-I)*AS(L+2-I))
25        AS(L+1-I) = AF(L+1-I)*X
26        DS(L+1-I) = (DF(L+1-I)-CF(L+1-I)*DS(L+2-I))*X
27      END DO
28 
29      XK(1)=DS(1)
30      DO I=2,L
31        XKB   = XK(I-1)
32        XK(I) = DS(I)-AS(I)*XKB
33      END DO
34
35      RETURN
36      END
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