Click or drag to resize

DORGBRRun Method

Purpose ======= DORGBR generates one of the real orthogonal matrices Q or P**T determined by DGEBRD when reducing a real matrix A to bidiagonal form: A = Q * B * P**T. Q and P**T are defined as products of elementary reflectors H(i) or G(i) respectively. If VECT = 'Q', A is assumed to have been an M-by-K matrix, and Q is of order M: if m .GE. k, Q = H(1) H(2) . . . H(k) and DORGBR returns the first n columns of Q, where m .GE. n .GE. k; if m .LT. k, Q = H(1) H(2) . . . H(m-1) and DORGBR returns Q as an M-by-M matrix. If VECT = 'P', A is assumed to have been a K-by-N matrix, and P**T is of order N: if k .LT. n, P**T = G(k) . . . G(2) G(1) and DORGBR returns the first m rows of P**T, where n .GE. m .GE. k; if k .GE. n, P**T = G(n-1) . . . G(2) G(1) and DORGBR returns P**T as an N-by-N matrix.

Namespace: DotNumerics.LinearAlgebra.CSLapack
Assembly: DWSIM.MathOps.DotNumerics (in DWSIM.MathOps.DotNumerics.dll) Version: 1.0.0.0 (1.0.0.0)
Syntax
Copy
public void Run(
	string VECT,
	int M,
	int N,
	int K,
	ref double[] A,
	int offset_a,
	int LDA,
	double[] TAU,
	int offset_tau,
	ref double[] WORK,
	int offset_work,
	int LWORK,
	ref int INFO
)
Request Example View Source

Parameters

VECT  String
(input) CHARACTER*1 Specifies whether the matrix Q or the matrix P**T is required, as defined in the transformation applied by DGEBRD: = 'Q': generate Q; = 'P': generate P**T.
M  Int32
(input) INTEGER The number of rows of the matrix Q or P**T to be returned. M .GE. 0.
N  Int32
(input) INTEGER The number of columns of the matrix Q or P**T to be returned. N .GE. 0. If VECT = 'Q', M .GE. N .GE. min(M,K); if VECT = 'P', N .GE. M .GE. min(N,K).
K  Int32
(input) INTEGER If VECT = 'Q', the number of columns in the original M-by-K matrix reduced by DGEBRD. If VECT = 'P', the number of rows in the original K-by-N matrix reduced by DGEBRD. K .GE. 0.
A  Double
(input/output) DOUBLE PRECISION array, dimension (LDA,N) On entry, the vectors which define the elementary reflectors, as returned by DGEBRD. On exit, the M-by-N matrix Q or P**T.
offset_a  Int32
 
LDA  Int32
(input) INTEGER The leading dimension of the array A. LDA .GE. max(1,M).
TAU  Double
(input) DOUBLE PRECISION array, dimension (min(M,K)) if VECT = 'Q' (min(N,K)) if VECT = 'P' TAU(i) must contain the scalar factor of the elementary reflector H(i) or G(i), which determines Q or P**T, as returned by DGEBRD in its array argument TAUQ or TAUP.
offset_tau  Int32
 
WORK  Double
(workspace/output) DOUBLE PRECISION array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
offset_work  Int32
 
LWORK  Int32
(input) INTEGER The dimension of the array WORK. LWORK .GE. max(1,min(M,N)). For optimum performance LWORK .GE. min(M,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
See Also