# sgtsl.f

          SUBROUTINE SGTSL (N, C, D, E, B, INFO)
    C***BEGIN PROLOGUE  SGTSL
    C***PURPOSE  Solve a tridiagonal linear system.
    C***LIBRARY   SLATEC (LINPACK)
    C***CATEGORY  D2A2A
    C***TYPE      SINGLE PRECISION (SGTSL-S, DGTSL-D, CGTSL-C)
    C***KEYWORDS  LINEAR ALGEBRA, LINPACK, MATRIX, SOLVE, TRIDIAGONAL
    C***AUTHOR  Dongarra, J., (ANL)
    C***DESCRIPTION
    C
    C     SGTSL given a general tridiagonal matrix and a right hand
    C     side will find the solution.
    C
    C     On Entry
    C
    C        N       INTEGER
    C                is the order of the tridiagonal matrix.
    C
    C        C       REAL(N)
    C                is the subdiagonal of the tridiagonal matrix.
    C                C(2) through C(N) should contain the subdiagonal.
    C                On output, C is destroyed.
    C
    C        D       REAL(N)
    C                is the diagonal of the tridiagonal matrix.
    C                On output, D is destroyed.
    C
    C        E       REAL(N)
    C                is the superdiagonal of the tridiagonal matrix.
    C                E(1) through E(N-1) should contain the superdiagonal.
    C                On output, E is destroyed.
    C
    C        B       REAL(N)
    C                is the right hand side vector.
    C
    C     On Return
    C
    C        B       is the solution vector.
    C
    C        INFO    INTEGER
    C                = 0 normal value.
    C                = K if the K-th element of the diagonal becomes
    C                    exactly zero.  The subroutine returns when
    C                    this is detected.
    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  (NONE)
    C***REVISION HISTORY  (YYMMDD)
    C   780814  DATE WRITTEN
    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  SGTSL