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NAME
     dposv - compute the solution to  a  real  system  of  linear
     equations  A * X = B,

SYNOPSIS
     SUBROUTINE DPOSV( UPLO, N, NRHS, A, LDA, B, LDB, INFO )

     CHARACTER UPLO

     INTEGER INFO, LDA, LDB, N, NRHS

     DOUBLE PRECISION A( LDA, * ), B( LDB, * )



     #include <sunperf.h>

     void dposv(char uplo, int n, int nrhs, double *a,  int  lda,
               double *db, int ldb, int *info) ;

PURPOSE
     DPOSV computes the solution to a real system of linear equa-
     tions
        A * X = B, where A is an N-by-N symmetric positive defin-
     ite matrix and X and B are N-by-NRHS matrices.

     The Cholesky decomposition is used to factor A as
        A = U**T* U,  if UPLO = 'U', or
        A = L * L**T,  if UPLO = 'L',
     where U is an upper triangular matrix and L is a lower  tri-
     angular  matrix.   The  factored  form  of A is then used to
     solve the system of equations A * X = B.


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

     N         (input) INTEGER
               The number of linear equations, i.e., 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.

     A         (input/output) DOUBLE PRECISION  array,  dimension
               (LDA,N)
               On entry, the symmetric matrix A.  If UPLO =  'U',
               the leading N-by-N upper triangular part of A con-
               tains the upper triangular part of the  matrix  A,
               and the strictly lower triangular part of A is not
               referenced.  If UPLO =  'L',  the  leading  N-by-N
               lower triangular part of A contains the lower tri-
               angular part of the matrix  A,  and  the  strictly
               upper triangular part of A is not referenced.

               On exit, if INFO = 0, the factor U or L  from  the
               Cholesky factorization A = U**T*U or A = L*L**T.

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

     B         (input/output) DOUBLE PRECISION  array,  dimension
               (LDB,NRHS)
               On entry, the N-by-NRHS right hand side matrix  B.
               On  exit,  if  INFO  =  0,  the N-by-NRHS 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 ille-
               gal value
               > 0:  if INFO = i, the leading minor of order i of
               A  is  not positive definite, so the factorization
               could not be completed, and the solution  has  not
               been computed.

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