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dsptrs

 NAME
      DSPTRS - solve a system of linear equations A*X = B with a
      real symmetric matrix A stored in packed format using the
      factorization A = U*D*U**T or A = L*D*L**T computed by
      DSPTRF

 SYNOPSIS
      SUBROUTINE DSPTRS( UPLO, N, NRHS, AP, IPIV, B, LDB, INFO )

          CHARACTER      UPLO

          INTEGER        INFO, LDB, N, NRHS

          INTEGER        IPIV( * )

          DOUBLE         PRECISION AP( * ), B( LDB, * )

 PURPOSE
      DSPTRS solves a system of linear equations A*X = B with a
      real symmetric matrix A stored in packed format using the
      factorization A = U*D*U**T or A = L*D*L**T computed by
      DSPTRF.

 ARGUMENTS
      UPLO    (input) CHARACTER*1
              Specifies whether the details of the factorization
              are stored as an upper or lower triangular matrix.
              = 'U':  Upper triangular, form is A = U*D*U**T;
              = 'L':  Lower triangular, form is A = L*D*L**T.

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

      NRHS    (input) INTEGER
              The number of right hand sides, i.e., the number of
              columns of the matrix B.  NRHS >= 0.

      AP      (input) DOUBLE PRECISION array, dimension (N*(N+1)/2)
              The block diagonal matrix D and the multipliers used
              to obtain the factor U or L as computed by DSPTRF,
              stored as a packed triangular matrix.

      IPIV    (input) INTEGER array, dimension (N)
              Details of the interchanges and the block structure
              of D as determined by DSPTRF.

 (LDB,NRHS)
      B       (input/output) DOUBLE PRECISION array, dimension
              On entry, the right hand side matrix B.  On exit,
              the solution matrix X.

      LDB     (input) INTEGER
              The leading dimension of the array B.  LDB >=
              max(1,N).

      INFO    (output) INTEGER
              = 0:  successful exit
              < 0: if INFO = -i, the i-th argument had an illegal
              value