# CentOS 7.0 - man page for cgeqpf (centos section 3)

cgeqpf.f(3) LAPACK cgeqpf.f(3)cgeqpf.fNAME-Functions/Subroutines subroutine cgeqpf (M, N, A, LDA, JPVT, TAU, WORK, RWORK, INFO) CGEQPFSYNOPSISFunction/Subroutine Documentation subroutine cgeqpf (integerM, integerN, complex, dimension( lda, * )A, integerLDA, integer, dimension( * )JPVT, complex, dimension( * )TAU, complex, dimension( * )WORK, real, dimension( * )RWORK, integerINFO) CGEQPF Purpose: This routine is deprecated and has been replaced by routine CGEQP3. CGEQPF computes a QR factorization with column pivoting of a complex M-by-N matrix A: A*P = Q*R. Parameters: M 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 >= 0 A A is COMPLEX array, dimension (LDA,N) On entry, the M-by-N matrix A. On exit, the upper triangle of the array contains the min(M,N)-by-N 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 i-th column of A is permuted to the front of A*P (a leading column); if JPVT(i) = 0, the i-th column of A is a free column. On exit, if JPVT(i) = k, then the i-th column of A*P was the k-th column of A. TAU TAU is COMPLEX array, dimension (min(M,N)) The scalar factors of the elementary reflectors. WORK WORK is COMPLEX array, dimension (N) RWORK RWORK is REAL array, dimension (2*N) INFO INFO is INTEGER = 0: successful exit < 0: if INFO =, the i-th argument had an illegal value Author: 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:i-1) = 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.-iApril 2011--For more details see LAPACK Working Note 176. Definition at line 149 of file cgeqpf.f.--AuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 cgeqpf.f(3)