dgesv.f(3)

NAME
dgesv.f -

SYNOPSIS

  Functions/Subroutines
subroutine dgesv (N, NRHS, A, LDA, IPIV, B, LDB, INFO)
DGESV computes the solution to system of linear equations A * X = B for GE matrices

Function/Subroutine Documentation

  subroutine dgesv (integerN, integerNRHS, double precision, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, double precision, dimension( ldb, * )B, integerLDB, integerINFO)

DGESV computes the solution to system of linear equations A * X = B for GE matrices

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.

Parameters:
    N

              N is INTEGER
              The number of linear equations, i.e., the order of the
              matrix A.  N >= 0.

    NRHS

              NRHS is INTEGER
              The number of right hand sides, i.e., the number of columns
              of the matrix B.  NRHS >= 0.

    A

              A is 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

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

    IPIV

              IPIV is 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

              B is 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

              LDB is INTEGER
              The leading dimension of the array B.  LDB >= max(1,N).

    INFO

              INFO is 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.

Author:
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Date:
    November 2011

Definition at line 123 of file dgesv.f.

Author

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