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dpptrs

 NAME
      DPPTRS - solve a system of linear equations A*X = B with a
      symmetric positive definite matrix A in packed storage using
      the Cholesky factorization A = U**T*U or A = L*L**T computed
      by DPPTRF

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

          CHARACTER      UPLO

          INTEGER        INFO, LDB, N, NRHS

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

 PURPOSE
      DPPTRS solves a system of linear equations A*X = B with a
      symmetric positive definite matrix A in packed storage using
      the Cholesky factorization A = U**T*U or A = L*L**T computed
      by DPPTRF.

 ARGUMENTS
      UPLO    (input) CHARACTER*1
              = 'U':  Upper triangle of A is stored;
              = 'L':  Lower triangle of A is stored.

      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 triangular factor U or L from the Cholesky fac-
              torization A = U**T*U or A = L*L**T, packed column-
              wise in a linear array.  The j-th column of U or L
              is stored in the array AP as follows: if UPLO = 'U',
              AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j; if UPLO =
              'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.

 (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