DGESL(3F)DGESL(3F)NAMEDGESL - DGESL solves the double precision system A * X = B or
TRANS(A) * X = B using the factors computed by DGECO or DGEFA.
SYNOPSYS
SUBROUTINE DGESL(A,LDA,N,IPVT,B,JOB)
DESCRIPTION
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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