dgesv man page on IRIX

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DGESV(3F)							     DGESV(3F)

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

SYNOPSIS
     SUBROUTINE DGESV( N, NRHS, A, LDA, IPIV, B, LDB, INFO )

	 INTEGER       INFO, LDA, LDB, N, NRHS

	 INTEGER       IPIV( * )

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

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.

									Page 1

DGESV(3F)							     DGESV(3F)

     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.

									Page 2

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