SGBSL(3F)

SGBSL - SGBSL solves the real band system A * X = B or TRANS(A) * X = B using the factors computed by SBGCO or SGBFA.

As shipped in IRIX 6.5.19. Unchanged since IRIX 6.5.

NAME
     SGBSL   - SGBSL solves the real band system A * X = B  or  TRANS(A) * X =
     B using the factors computed by SBGCO or SGBFA.


SYNOPSYS
      SUBROUTINE SGBSL(ABD,LDA,N,ML,MU,IPVT,B,JOB)

DESCRIPTION
     On Entry

     ABD REAL(LDA, N)
        the output from SBGCO or SGBFA.

     LDA INTEGER
        the leading dimension of the array  ABD .

     N INTEGER
        the order of the original matrix.

     ML INTEGER
        number of diagonals below the main diagonal.

     MU INTEGER
        number of diagonals above the main diagonal.

     IPVT INTEGER(N)
        the pivot vector from SBGCO or SGBFA.

     B REAL(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 SBGCO has set RCOND
     .GT. 0.0 or SGBFA has set INFO .EQ. 0 .  To compute  INVERSE(A) * C
     where  C  is a matrix with  P  columns
        CALL SBGCO(ABD,LDA,N,ML,MU,IPVT,RCOND,Z)
        If (RCOND is too small) GO TO ...
        DO 10 J = 1, P
        CALL SGBSL(ABD,LDA,N,ML,MU,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 SAXPY,SDOT Fortran MIN0