[u/mrichter/AliRoot.git] / MINICERN / packlib / kernlib / kerngen / tcgen / smxinv.F

*
* $Id$
*
* $Log$
* Revision 1.1.1.1  1996/02/15 17:49:53  mclareni
* Kernlib
*
*
#include "kerngen/pilot.h"
#if !defined(CERNLIB_TCGEN)
      SUBROUTINE SMXINV (A,NDIM,IFAIL)
C
C CERN PROGLIB# F107    SMXINV          .VERSION KERNFOR  1.0   720503
C ORIG. 03/05/72 CL
C
      DIMENSION A(*),INDEX(100),RI(100)
C
      DATA  TOL / 1.E-12/
C
      IFAIL=0
      N=NDIM
      NP1=N+1
         DO 10 I=1,N
   10 INDEX(I)=1
C
         DO 80 I=1,N
C
C--                FIND PIVOT
      PIVOT=0.
      JJ=1
         DO 20 J=1,N
      IF (INDEX(J).EQ.0) GO TO 19
      ELM=ABS (A(JJ))
      IF (ELM.LE.PIVOT) GO TO 19
      PIVOT=ELM
      K=J
      KK=JJ
   19 JJ=JJ+NP1
   20 CONTINUE
      IF (PIVOT/ABS(A(1)).LT.TOL) GO TO 100
      INDEX(K)=0
      PIVOT=-A(KK)
C
C--                ELIMINATION
      KJ=K
      NP=N
C
         DO 70 J=1,N
      IF (J-K) 34,30,34
C
   30 A(KJ)=1./PIVOT
      RI(J)=0.
      NP=1
      GO TO 70
C
   34 ELM=-A(KJ)
   40 RI(J)=ELM/PIVOT
      IF (ELM.EQ.0.) GO TO 50
C
      JL=J
         DO 45 L=1,J
      A(JL)=A(JL)+ELM*RI(L)
   45 JL=JL+N
C
   50 A(KJ)=RI(J)
C
   70 KJ=KJ+NP
C
   80 CONTINUE
C
C--                CHANGE THE SIGN AND PROVISIONAL FILL-UP
      IJ0=1
      JI0=1
         DO 95 I=1,N
      IJ=IJ0
      JI=JI0
C
         DO 90 J=1,I
      A(IJ)=-A(IJ)
      A(JI)=A(IJ)
      IJ=IJ+N
      JI=JI+1
   90 CONTINUE
C
      IJ0=IJ0+1
      JI0=JI0+N
   95 CONTINUE
      RETURN
C
C--                FAILURE RETURN
  100 IFAIL=1
      RETURN
      END
#endif
Commit	Line	Data
fe4da5cc	1	*
	2	* $Id$
	3	*
	4	* $Log$
	5	* Revision 1.1.1.1 1996/02/15 17:49:53 mclareni
	6	* Kernlib
	7	*
	8	*
	9	#include "kerngen/pilot.h"
	10	#if !defined(CERNLIB_TCGEN)
	11	SUBROUTINE SMXINV (A,NDIM,IFAIL)
	12	C
	13	C CERN PROGLIB# F107 SMXINV .VERSION KERNFOR 1.0 720503
	14	C ORIG. 03/05/72 CL
	15	C
	16	DIMENSION A(*),INDEX(100),RI(100)
	17	C
	18	DATA TOL / 1.E-12/
	19	C
	20	IFAIL=0
	21	N=NDIM
	22	NP1=N+1
	23	DO 10 I=1,N
	24	10 INDEX(I)=1
	25	C
	26	DO 80 I=1,N
	27	C
	28	C-- FIND PIVOT
	29	PIVOT=0.
	30	JJ=1
	31	DO 20 J=1,N
	32	IF (INDEX(J).EQ.0) GO TO 19
	33	ELM=ABS (A(JJ))
	34	IF (ELM.LE.PIVOT) GO TO 19
	35	PIVOT=ELM
	36	K=J
	37	KK=JJ
	38	19 JJ=JJ+NP1
	39	20 CONTINUE
	40	IF (PIVOT/ABS(A(1)).LT.TOL) GO TO 100
	41	INDEX(K)=0
	42	PIVOT=-A(KK)
	43	C
	44	C-- ELIMINATION
	45	KJ=K
	46	NP=N
	47	C
	48	DO 70 J=1,N
	49	IF (J-K) 34,30,34
	50	C
	51	30 A(KJ)=1./PIVOT
	52	RI(J)=0.
	53	NP=1
	54	GO TO 70
	55	C
	56	34 ELM=-A(KJ)
	57	40 RI(J)=ELM/PIVOT
	58	IF (ELM.EQ.0.) GO TO 50
	59	C
	60	JL=J
	61	DO 45 L=1,J
	62	A(JL)=A(JL)+ELM*RI(L)
	63	45 JL=JL+N
	64	C
65	50 A(KJ)=RI(J)
66	C
67	70 KJ=KJ+NP
68	C
69	80 CONTINUE
70	C
71	C-- CHANGE THE SIGN AND PROVISIONAL FILL-UP
72	IJ0=1
73	JI0=1
74	DO 95 I=1,N
75	IJ=IJ0
76	JI=JI0
77	C
78	DO 90 J=1,I
79	A(IJ)=-A(IJ)
80	A(JI)=A(IJ)
81	IJ=IJ+N
82	JI=JI+1
83	90 CONTINUE
84	C
85	IJ0=IJ0+1
86	JI0=JI0+N
87	95 CONTINUE
88	RETURN
89	C
90	C-- FAILURE RETURN
91	100 IFAIL=1
92	RETURN
93	END
94	#endif