[u/mrichter/AliRoot.git] / MINICERN / mathlib / gen / divon / ldlsol.F

*
* $Id$
*
* $Log$
* Revision 1.1.1.1  1996/04/01 15:03:27  mclareni
* Mathlib gen
*
*
#include "gen/pilot.h"
      SUBROUTINE LDLSOL (N,NADIM,CHOL,B,X)
      INTEGER N, NADIM
      DOUBLE PRECISION CHOL(NADIM, N)
      DOUBLE PRECISION B(N), X(N)
      INTEGER I, IM1, J, JJ, JP1
      DOUBLE PRECISION SUM
      X(1)=B(1)
      IF(N.EQ.1) GOTO 30
      DO 20 I=2,N
      SUM=B(I)
      IM1=I-1
      DO 10 J=1,IM1
      SUM=SUM-CHOL(I,J)*X(J)
 10   CONTINUE
      X(I)=SUM
 20   CONTINUE
 30   IF(CHOL(N,N).LE.0.0D+0) RETURN
      X(N)=X(N)/CHOL(N,N)
      IF(N.EQ.1) RETURN
      DO 50 JJ=2,N
      J=N-JJ+1
      IF(CHOL(J,J).LE.0.0D+0) RETURN
      SUM=X(J)/CHOL(J,J)
      JP1=J+1
      DO 40 I=JP1,N
      SUM=SUM-CHOL(I,J)*X(I)
 40   CONTINUE
      X(J)=SUM
 50   CONTINUE
      RETURN
      END
Commit	Line	Data
fe4da5cc	1	*
	2	* $Id$
	3	*
	4	* $Log$
	5	* Revision 1.1.1.1 1996/04/01 15:03:27 mclareni
	6	* Mathlib gen
	7	*
	8	*
	9	#include "gen/pilot.h"
	10	SUBROUTINE LDLSOL (N,NADIM,CHOL,B,X)
	11	INTEGER N, NADIM
	12	DOUBLE PRECISION CHOL(NADIM, N)
	13	DOUBLE PRECISION B(N), X(N)
	14	INTEGER I, IM1, J, JJ, JP1
	15	DOUBLE PRECISION SUM
	16	X(1)=B(1)
	17	IF(N.EQ.1) GOTO 30
	18	DO 20 I=2,N
	19	SUM=B(I)
	20	IM1=I-1
	21	DO 10 J=1,IM1
	22	SUM=SUM-CHOL(I,J)*X(J)
	23	10 CONTINUE
	24	X(I)=SUM
	25	20 CONTINUE
	26	30 IF(CHOL(N,N).LE.0.0D+0) RETURN
	27	X(N)=X(N)/CHOL(N,N)
	28	IF(N.EQ.1) RETURN
	29	DO 50 JJ=2,N
	30	J=N-JJ+1
	31	IF(CHOL(J,J).LE.0.0D+0) RETURN
	32	SUM=X(J)/CHOL(J,J)
	33	JP1=J+1
	34	DO 40 I=JP1,N
	35	SUM=SUM-CHOL(I,J)*X(I)
	36	40 CONTINUE
	37	X(J)=SUM
	38	50 CONTINUE
	39	RETURN
	40	END