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  struc­
               ture of D as determined by DSPTRF.

       B         (input/output)   DOUBLE   PRECISION   array,
               dimension (LDB,NRHS)
               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  >=


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


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