pure functiondgesv

Information

Lapack documentation
    Purpose
    =======

    DGESV computes the solution to a real system of linear equations
       A * X = B,
    where A is an N-by-N matrix and X and B are N-by-NRHS matrices.

    The LU decomposition with partial pivoting and row interchanges is
    used to factor A as
       A = P * L * U,
    where P is a permutation matrix, L is unit lower triangular, and U is
    upper triangular.  The factored form of A is then used to solve the
    system of equations A * X = B.

    Arguments
    =========

    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 N-by-N coefficient matrix A.
            On exit, the factors L and U from the factorization
            A = P*L*U; the unit diagonal elements of L are not stored.

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

    IPIV    (output) INTEGER array, dimension (N)
            The pivot indices that define the permutation matrix P;
            row i of the matrix was interchanged with row IPIV(i).

    B       (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
            On entry, the N-by-NRHS matrix of 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, U(i,i) is exactly zero.  The factorization
                  has been completed, but the factor U is exactly
                  singular, so the solution could not be computed.

Inputs

Outputs