strid(3S)

NAME
     STRID - compute the solution to a real system of linear equations A*x =
     b, where A is an N-by-N tridiagonal matrix, and x and b are vectors of
     length N

SYNOPSIS
     SUBROUTINE STRID( N, DL, D, DU, B )

         INTEGER       N

         REAL          DL( * ), D( * ), DU( * ), B( * )

IMPLEMENTATION
     These routines are part of the SCSL Scientific Library and can be loaded
     using either the -lscs or the -lscs_mp option.  The -lscs_mp option
     directs the linker to use the multi-processor version of the library.

     When linking to SCSL with -lscs or -lscs_mp, the default integer size is
     4 bytes (32 bits). Another version of SCSL is available in which integers
     are 8 bytes (64 bits).  This version allows the user access to larger
     memory sizes and helps when porting legacy Cray codes.  It can be loaded
     by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
     only one of the two versions; 4-byte integer and 8-byte integer library
     calls cannot be mixed.

PURPOSE
     STRID computes the solution of a tridiagonal system of linear equations
     A*x = b using a "burn-at-both-ends" algorithm.  NO PIVOTING FOR STABILITY
     IS DONE.


ARGUMENTS
     N       (input) INTEGER
             The order of the matrix A.  N >= 0.

     DL      (input/output) REAL array, dimension (N-1)
             On entry, the (N-1) subdiagonal elements of the tridiagonal
             matrix A.  On exit, DL is overwritten.

     D       (input/output) REAL array, dimension (N)
             On entry, the N diagonal elements of the tridiagonal matrix A.
             On exit, D is overwritten.

     DU      (input/output) REAL array, dimension (N-1)
             On entry, the (N-1) superdiagonal elements of the tridiagonal
             matrix A.  On exit, DU is overwritten.

     B       (input/output) REAL array, dimension (N)
             On entry, the N-element right hand side vector b.  On exit, the
             N-element solution vector x.
SEE ALSO
     INTRO_LAPACK(3S), INTRO_SCSL(3S)

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