dgbsl.f
SUBROUTINE DGBSL (ABD, LDA, N, ML, MU, IPVT, B, JOB)
C***BEGIN PROLOGUE DGBSL
C***PURPOSE Solve the real band system A*X=B or TRANS(A)*X=B using
C the factors computed by DGBCO or DGBFA.
C***LIBRARY SLATEC (LINPACK)
C***CATEGORY D2A2
C***TYPE DOUBLE PRECISION (SGBSL-S, DGBSL-D, CGBSL-C)
C***KEYWORDS BANDED, LINEAR ALGEBRA, LINPACK, MATRIX, SOLVE
C***AUTHOR Moler, C. B., (U. of New Mexico)
C***DESCRIPTION
C
C DGBSL solves the double precision band system
C A * X = B or TRANS(A) * X = B
C using the factors computed by DGBCO or DGBFA.
C
C On Entry
C
C ABD DOUBLE PRECISION(LDA, N)
C the output from DGBCO or DGBFA.
C
C LDA INTEGER
C the leading dimension of the array ABD .
C
C N INTEGER
C the order of the original matrix.
C
C ML INTEGER
C number of diagonals below the main diagonal.
C
C MU INTEGER
C number of diagonals above the main diagonal.
C
C IPVT INTEGER(N)
C the pivot vector from DGBCO or DGBFA.
C
C B DOUBLE PRECISION(N)
C the right hand side vector.
C
C JOB INTEGER
C = 0 to solve A*X = B ,
C = nonzero to solve TRANS(A)*X = B , where
C TRANS(A) is the transpose.
C
C On Return
C
C B the solution vector X .
C
C Error Condition
C
C A division by zero will occur if the input factor contains a
C zero on the diagonal. Technically this indicates singularity
C but it is often caused by improper arguments or improper
C setting of LDA . It will not occur if the subroutines are
C called correctly and if DGBCO has set RCOND .GT. 0.0
C or DGBFA has set INFO .EQ. 0 .
C
C To compute INVERSE(A) * C where C is a matrix
C with P columns
C CALL DGBCO(ABD,LDA,N,ML,MU,IPVT,RCOND,Z)
C IF (RCOND is too small) GO TO ...
C DO 10 J = 1, P
C CALL DGBSL(ABD,LDA,N,ML,MU,IPVT,C(1,J),0)
C 10 CONTINUE
C
C***REFERENCES J. J. Dongarra, J. R. Bunch, C. B. Moler, and G. W.
C Stewart, LINPACK Users' Guide, SIAM, 1979.
C***ROUTINES CALLED DAXPY, DDOT
C***REVISION HISTORY (YYMMDD)
C 780814 DATE WRITTEN
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890831 Modified array declarations. (WRB)
C 890831 REVISION DATE from Version 3.2
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900326 Removed duplicate information from DESCRIPTION section.
C (WRB)
C 920501 Reformatted the REFERENCES section. (WRB)
C***END PROLOGUE DGBSL