DLAED1Run Method

Purpose ======= DLAED1 computes the updated eigensystem of a diagonal matrix after modification by a rank-one symmetric matrix. This routine is used only for the eigenproblem which requires all eigenvalues and eigenvectors of a tridiagonal matrix. DLAED7 handles the case in which eigenvalues only or eigenvalues and eigenvectors of a full symmetric matrix (which was reduced to tridiagonal form) are desired. T = Q(in) ( D(in) + RHO * Z*Z' ) Q'(in) = Q(out) * D(out) * Q'(out) where Z = Q'u, u is a vector of length N with ones in the CUTPNT and CUTPNT + 1 th elements and zeros elsewhere. The eigenvectors of the original matrix are stored in Q, and the eigenvalues are in D. The algorithm consists of three stages: The first stage consists of deflating the size of the problem when there are multiple eigenvalues or if there is a zero in the Z vector. For each such occurence the dimension of the secular equation problem is reduced by one. This stage is performed by the routine DLAED2. The second stage consists of calculating the updated eigenvalues. This is done by finding the roots of the secular equation via the routine DLAED4 (as called by DLAED3). This routine also calculates the eigenvectors of the current problem. The final stage consists of computing the updated eigenvectors directly using the updated eigenvalues. The eigenvectors for the current problem are multiplied with the eigenvectors from the overall problem.

public void Run(
	int N,
	ref double[] D,
	int offset_d,
	ref double[] Q,
	int offset_q,
	int LDQ,
	ref int[] INDXQ,
	int offset_indxq,
	ref double RHO,
	int CUTPNT,
	ref double[] WORK,
	int offset_work,
	ref int[] IWORK,
	int offset_iwork,
	ref int INFO
)

Public Sub Run ( 
	N As Integer,
	ByRef D As Double(),
	offset_d As Integer,
	ByRef Q As Double(),
	offset_q As Integer,
	LDQ As Integer,
	ByRef INDXQ As Integer(),
	offset_indxq As Integer,
	ByRef RHO As Double,
	CUTPNT As Integer,
	ByRef WORK As Double(),
	offset_work As Integer,
	ByRef IWORK As Integer(),
	offset_iwork As Integer,
	ByRef INFO As Integer
)