table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/ztpqrt.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/ztpqrt.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/ztpqrt.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine ZTPQRT (m, n, l, nb, a, lda, b, ldb, t, ldt,
work, info)
ZTPQRT
Function/Subroutine Documentation¶
subroutine ZTPQRT (integer m, integer n, integer l, integer nb, complex*16, dimension( lda, * ) a, integer lda, complex*16, dimension( ldb, * ) b, integer ldb, complex*16, dimension( ldt, * ) t, integer ldt, complex*16, dimension( * ) work, integer info)¶
ZTPQRT
Purpose:
!> !> ZTPQRT computes a blocked QR factorization of a complex !> matrix C, which is composed of a !> triangular block A and pentagonal block B, using the compact !> WY representation for Q. !>
Parameters
M
!> M is INTEGER !> The number of rows of the matrix B. !> M >= 0. !>
N
!> N is INTEGER !> The number of columns of the matrix B, and the order of the !> triangular matrix A. !> N >= 0. !>
L
!> L is INTEGER !> The number of rows of the upper trapezoidal part of B. !> MIN(M,N) >= L >= 0. See Further Details. !>
NB
!> NB is INTEGER !> The block size to be used in the blocked QR. N >= NB >= 1. !>
A
!> A is COMPLEX*16 array, dimension (LDA,N) !> On entry, the upper triangular N-by-N matrix A. !> On exit, the elements on and above the diagonal of the array !> contain the upper triangular matrix R. !>
LDA
!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(1,N). !>
B
!> B is COMPLEX*16 array, dimension (LDB,N) !> On entry, the pentagonal M-by-N matrix B. The first M-L rows !> are rectangular, and the last L rows are upper trapezoidal. !> On exit, B contains the pentagonal matrix V. See Further Details. !>
LDB
!> LDB is INTEGER !> The leading dimension of the array B. LDB >= max(1,M). !>
T
!> T is COMPLEX*16 array, dimension (LDT,N) !> The upper triangular block reflectors stored in compact form !> as a sequence of upper triangular blocks. See Further Details. !>
LDT
!> LDT is INTEGER !> The leading dimension of the array T. LDT >= NB. !>
WORK
!> WORK is COMPLEX*16 array, dimension (NB*N) !>
INFO
!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument had an illegal value !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> The input matrix C is a (N+M)-by-N matrix !> !> C = [ A ] !> [ B ] !> !> where A is an upper triangular N-by-N matrix, and B is M-by-N pentagonal !> matrix consisting of a (M-L)-by-N rectangular matrix B1 on top of a L-by-N !> upper trapezoidal matrix B2: !> !> B = [ B1 ] <- (M-L)-by-N rectangular !> [ B2 ] <- L-by-N upper trapezoidal. !> !> The upper trapezoidal matrix B2 consists of the first L rows of a !> N-by-N upper triangular matrix, where 0 <= L <= MIN(M,N). If L=0, !> B is rectangular M-by-N; if M=L=N, B is upper triangular. !> !> The matrix W stores the elementary reflectors H(i) in the i-th column !> below the diagonal (of A) in the (N+M)-by-N input matrix C !> !> C = [ A ] <- upper triangular N-by-N !> [ B ] <- M-by-N pentagonal !> !> so that W can be represented as !> !> W = [ I ] <- identity, N-by-N !> [ V ] <- M-by-N, same form as B. !> !> Thus, all of information needed for W is contained on exit in B, which !> we call V above. Note that V has the same form as B; that is, !> !> V = [ V1 ] <- (M-L)-by-N rectangular !> [ V2 ] <- L-by-N upper trapezoidal. !> !> The columns of V represent the vectors which define the H(i)'s. !> !> The number of blocks is B = ceiling(N/NB), where each !> block is of order NB except for the last block, which is of order !> IB = N - (B-1)*NB. For each of the B blocks, a upper triangular block !> reflector factor is computed: T1, T2, ..., TB. The NB-by-NB (and IB-by-IB !> for the last block) T's are stored in the NB-by-N matrix T as !> !> T = [T1 T2 ... TB]. !>
Definition at line 187 of file ztpqrt.f.
Author¶
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