CPOSV(3)              LAPACK driver routine (version 3.1)             CPOSV(3)



NAME
       CPOSV  -  the solution to a complex system of linear equations  A * X =
       B,

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

           CHARACTER     UPLO

           INTEGER       INFO, LDA, LDB, N, NRHS

           COMPLEX       A( LDA, * ), B( LDB, * )

PURPOSE
       CPOSV computes the solution to a complex system of linear equations
          A * X = B, where A is an N-by-N Hermitian positive  definite  matrix
       and X and B are N-by-NRHS matrices.

       The Cholesky decomposition is used to factor A as
          A = U**H* U,  if UPLO = 'U', or
          A = L * L**H,  if UPLO = 'L',
       where  U  is  an  upper  triangular matrix and  L is a lower triangular
       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) COMPLEX array, dimension (LDA,N)
               On  entry,  the Hermitian matrix A.  If UPLO = 'U', the leading
               N-by-N upper triangular part of A contains 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 triangular 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 fac-
               torization A = U**H*U or A = L*L**H.

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

       B       (input/output) COMPLEX 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 illegal 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.



 LAPACK driver routine (version 3.N1o)vember 2006                        CPOSV(3)