Provided by: liblapack-doc_3.3.1-1_all bug


       LAPACK-3 - computes the solution to a real system of linear equations  A * X = B,



           CHARACTER     UPLO

           INTEGER       INFO, LDB, N, NRHS

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


       DPPSV computes the solution to a real system of linear equations
          A * X = B,
        where A is an N-by-N symmetric positive definite matrix stored in
        packed format 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 triangular
        matrix.  The factored form of A is then used to solve the system of
        equations A * X = B.


        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.

        AP      (input/output) DOUBLE PRECISION array, dimension (N*(N+1)/2)
                On entry, the upper or lower triangle of the symmetric matrix
                A, packed columnwise in a linear array.  The j-th column of A
                is stored in the array AP as follows:
                if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
                if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.
                See below for further details.
                On exit, if INFO = 0, the factor U or L from the Cholesky
                factorization A = U**T*U or A = L*L**T, in the same storage
                format as A.

        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 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.


        The packed storage scheme is illustrated by the following example
        when N = 4, UPLO = 'U':
        Two-dimensional storage of the symmetric matrix A:
           a11 a12 a13 a14
               a22 a23 a24
                   a33 a34     (aij = conjg(aji))
        Packed storage of the upper triangle of A:
        AP = [ a11, a12, a22, a13, a23, a33, a14, a24, a34, a44 ]

 LAPACK driver routine (version 3.3.1)      April 2011                             DPPSV(3lapack)