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Commit | Line | Data |
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fe4da5cc | 1 | * |
2 | * $Id$ | |
3 | * | |
4 | * $Log$ | |
5 | * Revision 1.1.1.1 1996/02/15 17:48:49 mclareni | |
6 | * Kernlib | |
7 | * | |
8 | * | |
9 | #include "kernnum/pilot.h" | |
10 | SUBROUTINE DINV(N,A,IDIM,R,IFAIL) | |
11 | REAL R(N),T1,T2,T3 | |
12 | DOUBLE PRECISION A(IDIM,N),DET,TEMP,S, | |
13 | $ C11,C12,C13,C21,C22,C23,C31,C32,C33 | |
14 | CHARACTER*6 NAME | |
15 | DATA NAME/'DINV'/,KPRNT/0/ | |
16 | C | |
17 | C ****************************************************************** | |
18 | C | |
19 | C REPLACES A BY ITS INVERSE. | |
20 | C | |
21 | C (PARAMETERS AS FOR DEQINV.) | |
22 | C | |
23 | C CALLS ... DFACT, DFINV, F010PR, ABEND. | |
24 | C | |
25 | C ****************************************************************** | |
26 | C | |
27 | C TEST FOR PARAMETER ERRORS. | |
28 | C | |
29 | IF((N.LT.1).OR.(N.GT.IDIM)) GO TO 7 | |
30 | C | |
31 | C TEST FOR N.LE.3. | |
32 | C | |
33 | IF(N.GT.3) GO TO 6 | |
34 | IFAIL=0 | |
35 | IF(N.LT.3) GO TO 4 | |
36 | C | |
37 | C N=3 CASE. | |
38 | C | |
39 | C COMPUTE COFACTORS. | |
40 | C11=A(2,2)*A(3,3)-A(2,3)*A(3,2) | |
41 | C12=A(2,3)*A(3,1)-A(2,1)*A(3,3) | |
42 | C13=A(2,1)*A(3,2)-A(2,2)*A(3,1) | |
43 | C21=A(3,2)*A(1,3)-A(3,3)*A(1,2) | |
44 | C22=A(3,3)*A(1,1)-A(3,1)*A(1,3) | |
45 | C23=A(3,1)*A(1,2)-A(3,2)*A(1,1) | |
46 | C31=A(1,2)*A(2,3)-A(1,3)*A(2,2) | |
47 | C32=A(1,3)*A(2,1)-A(1,1)*A(2,3) | |
48 | C33=A(1,1)*A(2,2)-A(1,2)*A(2,1) | |
49 | T1=ABS(SNGL(A(1,1))) | |
50 | T2=ABS(SNGL(A(2,1))) | |
51 | T3=ABS(SNGL(A(3,1))) | |
52 | C | |
53 | C (SET TEMP=PIVOT AND DET=PIVOT*DET.) | |
54 | IF(T1.GE.T2) GO TO 1 | |
55 | IF(T3.GE.T2) GO TO 2 | |
56 | C (PIVOT IS A21) | |
57 | TEMP=A(2,1) | |
58 | DET=C13*C32-C12*C33 | |
59 | GO TO 3 | |
60 | 1 IF(T3.GE.T1) GO TO 2 | |
61 | C (PIVOT IS A11) | |
62 | TEMP=A(1,1) | |
63 | DET=C22*C33-C23*C32 | |
64 | GO TO 3 | |
65 | C (PIVOT IS A31) | |
66 | 2 TEMP=A(3,1) | |
67 | DET=C23*C12-C22*C13 | |
68 | C | |
69 | C SET ELEMENTS OF INVERSE IN A. | |
70 | 3 IF(DET.EQ.0D0) GO TO 8 | |
71 | S=TEMP/DET | |
72 | A(1,1)=S*C11 | |
73 | A(1,2)=S*C21 | |
74 | A(1,3)=S*C31 | |
75 | A(2,1)=S*C12 | |
76 | A(2,2)=S*C22 | |
77 | A(2,3)=S*C32 | |
78 | A(3,1)=S*C13 | |
79 | A(3,2)=S*C23 | |
80 | A(3,3)=S*C33 | |
81 | RETURN | |
82 | C | |
83 | 4 IF(N.LT.2) GO TO 5 | |
84 | C | |
85 | C N=2 CASE BY CRAMERS RULE. | |
86 | C | |
87 | DET=A(1,1)*A(2,2)-A(1,2)*A(2,1) | |
88 | IF(DET.EQ.0D0) GO TO 8 | |
89 | S=1D0/DET | |
90 | C11 =S*A(2,2) | |
91 | A(1,2)=-S*A(1,2) | |
92 | A(2,1)=-S*A(2,1) | |
93 | A(2,2)=S*A(1,1) | |
94 | A(1,1)=C11 | |
95 | RETURN | |
96 | C | |
97 | C N=1 CASE. | |
98 | C | |
99 | 5 IF(A(1,1).EQ.0D0) GO TO 8 | |
100 | A(1,1)=1D0/A(1,1) | |
101 | RETURN | |
102 | C | |
103 | C N.GT.3 CASES. FACTORIZE MATRIX AND INVERT. | |
104 | C | |
105 | 6 CALL DFACT(N,A,IDIM,R,IFAIL,DET,JFAIL) | |
106 | IF(IFAIL.NE.0) RETURN | |
107 | CALL DFINV(N,A,IDIM,R) | |
108 | RETURN | |
109 | C | |
110 | C ERROR EXITS. | |
111 | C | |
112 | 7 IFAIL=+1 | |
113 | CALL F010PR(NAME,N,IDIM,K,KPRNT) | |
114 | RETURN | |
115 | C | |
116 | 8 IFAIL=-1 | |
117 | RETURN | |
118 | C | |
119 | END |