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DGBTF2Run Method

Purpose ======= DGBTF2 computes an LU factorization of a real m-by-n band matrix A using partial pivoting with row interchanges. This is the unblocked version of the algorithm, calling Level 2 BLAS.

Namespace: DotNumerics.LinearAlgebra.CSLapack
Assembly: DWSIM.MathOps.DotNumerics (in DWSIM.MathOps.DotNumerics.dll) Version: 1.0.0.0 (1.0.0.0)
Syntax
public void Run(
	int M,
	int N,
	int KL,
	int KU,
	ref double[] AB,
	int offset_ab,
	int LDAB,
	ref int[] IPIV,
	int offset_ipiv,
	ref int INFO
)
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Parameters

M  Int32
(input) INTEGER The number of rows of the matrix A. M .GE. 0.
N  Int32
(input) INTEGER The number of columns of the matrix A. N .GE. 0.
KL  Int32
(input) INTEGER The number of subdiagonals within the band of A. KL .GE. 0.
KU  Int32
(input) INTEGER The number of superdiagonals within the band of A. KU .GE. 0.
AB  Double
(input/output) DOUBLE PRECISION array, dimension (LDAB,N) On entry, the matrix A in band storage, in rows KL+1 to 2*KL+KU+1; rows 1 to KL of the array need not be set. The j-th column of A is stored in the j-th column of the array AB as follows: AB(kl+ku+1+i-j,j) = A(i,j) for max(1,j-ku).LE.i.LE.min(m,j+kl) On exit, details of the factorization: U is stored as an upper triangular band matrix with KL+KU superdiagonals in rows 1 to KL+KU+1, and the multipliers used during the factorization are stored in rows KL+KU+2 to 2*KL+KU+1. See below for further details.
offset_ab  Int32
 
LDAB  Int32
(input) INTEGER The leading dimension of the array AB. LDAB .GE. 2*KL+KU+1.
IPIV  Int32
(output) INTEGER array, dimension (min(M,N)) The pivot indices; for 1 .LE. i .LE. min(M,N), row i of the matrix was interchanged with row IPIV(i).
offset_ipiv  Int32
 
INFO  Int32
(output) INTEGER = 0: successful exit .LT. 0: if INFO = -i, the i-th argument had an illegal value .GT. 0: if INFO = +i, U(i,i) is exactly zero. The factorization has been completed, but the factor U is exactly singular, and division by zero will occur if it is used to solve a system of equations.
See Also