DGEHRDRun Method

public void Run(
	int N,
	int ILO,
	int IHI,
	ref double[] A,
	int offset_a,
	int LDA,
	ref double[] TAU,
	int offset_tau,
	ref double[] WORK,
	int offset_work,
	int LWORK,
	ref int INFO
)

Public Sub Run ( 
	N As Integer,
	ILO As Integer,
	IHI As Integer,
	ByRef A As Double(),
	offset_a As Integer,
	LDA As Integer,
	ByRef TAU As Double(),
	offset_tau As Integer,
	ByRef WORK As Double(),
	offset_work As Integer,
	LWORK As Integer,
	ByRef INFO As Integer
)

Parameters

N  Int32

(input) INTEGER The order of the matrix A. N .GE. 0.

ILO  Int32

(input) INTEGER

IHI  Int32

(input) INTEGER It is assumed that A is already upper triangular in rows and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally set by a previous call to DGEBAL; otherwise they should be set to 1 and N respectively. See Further Details. 1 .LE. ILO .LE. IHI .LE. N, if N .GT. 0; ILO=1 and IHI=0, if N=0.

A  Double

(input/output) DOUBLE PRECISION array, dimension (LDA,N) On entry, the N-by-N general matrix to be reduced. On exit, the upper triangle and the first subdiagonal of A are overwritten with the upper Hessenberg matrix H, and the elements below the first subdiagonal, with the array TAU, represent the orthogonal matrix Q as a product of elementary reflectors. See Further Details.

offset_a  Int32

 

LDA  Int32

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

TAU  Double

(output) DOUBLE PRECISION array, dimension (N-1) The scalar factors of the elementary reflectors (see Further Details). Elements 1:ILO-1 and IHI:N-1 of TAU are set to zero.

offset_tau  Int32

 

WORK  Double

(workspace/output) DOUBLE PRECISION array, dimension (LWORK) On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

offset_work  Int32

 

LWORK  Int32

(input) INTEGER The length of the array WORK. LWORK .GE. max(1,N). For optimum performance LWORK .GE. N*NB, where NB is the optimal blocksize. If LWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA.

INFO  Int32

(output) INTEGER = 0: successful exit .LT. 0: if INFO = -i, the i-th argument had an illegal value.

Reference