DGESL(3F)							     DGESL(3F)

NAME    [Toc]    [Back]

     DGESL   - DGESL solves the	double precision system	A * X =	B  or
     TRANS(A) *	X = B using the	factors	computed by DGECO or DGEFA.

SYNOPSYS    [Toc]    [Back]

      SUBROUTINE DGESL(A,LDA,N,IPVT,B,JOB)

DESCRIPTION    [Toc]    [Back]

     On	Entry

     A DOUBLE PRECISION(LDA, N)
	the output from	DGECO or DGEFA.

     LDA INTEGER
	the leading dimension of the array  A .

     N INTEGER
	the order of the matrix	 A .

     IPVT INTEGER(N)
	the pivot vector from DGECO or DGEFA.

     B DOUBLE PRECISION(N)
	the right hand side vector.

     JOB INTEGER
	= 0	    to solve  A*X = B ,
	= nonzero   to solve  TRANS(A)*X = B  where
	TRANS(A)  is the transpose.  On	Return

     B the solution vector  X .	Error Condition

     A division	by zero	will occur if the input	factor contains	a zero on the
     diagonal.	Technically this indicates singularity but it is often caused
     by	improper arguments or improper setting of LDA .	 It will not occur if
     the subroutines are called	correctly and if DGECO has set RCOND .GT. 0.0
     or	DGEFA has set INFO .EQ.	0 .  To	compute	 INVERSE(A) * C	 where	C  is
     a matrix with  P  columns
	CALL DGECO(A,LDA,N,IPVT,RCOND,Z)
	IF (RCOND is too small)	GO TO ...
	DO 10 J	= 1, P
	CALL DGESL(A,LDA,N,IPVT,C(1,J),0) 10 CONTINUE LINPACK.	This version
     dated 08/14/78 .  Cleve Moler, University of New Mexico, Argonne National
     Lab.  Subroutines and Functions BLAS DAXPY,DDOT


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