snbsl.f
SUBROUTINE SNBSL (ABE, LDA, N, ML, MU, IPVT, B, JOB)
C***BEGIN PROLOGUE SNBSL
C***PURPOSE Solve a real band system using the factors computed by
C SNBCO or SNBFA.
C***LIBRARY SLATEC
C***CATEGORY D2A2
C***TYPE SINGLE PRECISION (SNBSL-S, DNBSL-D, CNBSL-C)
C***KEYWORDS BANDED, LINEAR EQUATIONS, NONSYMMETRIC, SOLVE
C***AUTHOR Voorhees, E. A., (LANL)
C***DESCRIPTION
C
C SNBSL solves the real band system
C A * X = B or TRANS(A) * X = B
C using the factors computed by SNBCO or SNBFA.
C
C On Entry
C
C ABE REAL(LDA, NC)
C the output from SNBCO or SNBFA.
C NC must be .GE. 2*ML+MU+1 .
C
C LDA INTEGER
C the leading dimension of the array ABE .
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 SNBCO or SNBFA.
C
C B REAL(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 SNBCO has set RCOND .GT. 0.0
C or SNBFA has set INFO .EQ. 0 .
C
C To compute INVERSE(A) * C where C is a matrix
C with P columns
C CALL SNBCO(ABE,LDA,N,ML,MU,IPVT,RCOND,Z)
C IF (RCOND is too small) GO TO ...
C DO 10 J = 1, P
C CALL SNBSL(ABE,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 SAXPY, SDOT
C***REVISION HISTORY (YYMMDD)
C 800717 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 920501 Reformatted the REFERENCES section. (WRB)
C***END PROLOGUE SNBSL