
NAMEzgeqpf.f SYNOPSISFunctions/Subroutinessubroutine zgeqpf (M, N, A, LDA, JPVT, TAU, WORK, RWORK, INFO) Function/Subroutine Documentationsubroutine zgeqpf (integerM, integerN, complex*16, dimension( lda, * )A, integerLDA, integer, dimension( * )JPVT, complex*16, dimension( * )TAU, complex*16, dimension( * )WORK, double precision, dimension( * )RWORK, integerINFO)ZGEQPF Purpose:This routine is deprecated and has been replaced by routine ZGEQP3. ZGEQPF computes a QR factorization with column pivoting of a complex MbyN matrix A: A*P = Q*R. M
Author:
M is INTEGER The number of rows of the matrix A. M >= 0.N N is INTEGER The number of columns of the matrix A. N >= 0A A is COMPLEX*16 array, dimension (LDA,N) On entry, the MbyN matrix A. On exit, the upper triangle of the array contains the min(M,N)byN upper triangular matrix R; the elements below the diagonal, together with the array TAU, represent the unitary matrix Q as a product of min(m,n) elementary reflectors.LDA LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M).JPVT JPVT is INTEGER array, dimension (N) On entry, if JPVT(i) .ne. 0, the ith column of A is permuted to the front of A*P (a leading column); if JPVT(i) = 0, the ith column of A is a free column. On exit, if JPVT(i) = k, then the ith column of A*P was the kth column of A.TAU TAU is COMPLEX*16 array, dimension (min(M,N)) The scalar factors of the elementary reflectors.WORK WORK is COMPLEX*16 array, dimension (N)RWORK RWORK is DOUBLE PRECISION array, dimension (2*N)INFO INFO is INTEGER = 0: successful exit < 0: if INFO = i, the ith argument had an illegal value Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011
Further Details:
The matrix Q is represented as a product of elementary reflectors Q = H(1) H(2) . . . H(n) Each H(i) has the form H = I  tau * v * v**H where tau is a complex scalar, and v is a complex vector with v(1:i1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i). The matrix P is represented in jpvt as follows: If jpvt(j) = i then the jth column of P is the ith canonical unit vector. Partial column norm updating strategy modified by Z. Drmac and Z. Bujanovic, Dept. of Mathematics, University of Zagreb, Croatia.  April 2011  For more details see LAPACK Working Note 176. AuthorGenerated automatically by Doxygen for LAPACK from the source code.
Visit the GSP FreeBSD Man Page Interface. 