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LAPACK
3.7.0
LAPACK: Linear Algebra PACKage
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subroutine cgeqpf | ( | integer | M, |
integer | N, | ||
complex, dimension( lda, * ) | A, | ||
integer | LDA, | ||
integer, dimension( * ) | JPVT, | ||
complex, dimension( * ) | TAU, | ||
complex, dimension( * ) | WORK, | ||
real, dimension( * ) | RWORK, | ||
integer | INFO | ||
) |
CGEQPF
Download CGEQPF + dependencies [TGZ] [ZIP] [TXT]
This routine is deprecated and has been replaced by routine CGEQP3.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.
[in] | M | M is INTEGER The number of rows of the matrix A. M >= 0. |
[in] | N | N is INTEGER The number of columns of the matrix A. N >= 0 |
[in,out] | 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. |
[in] | LDA | LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M). |
[in,out] | 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. |
[out] | TAU | TAU is COMPLEX array, dimension (min(M,N)) The scalar factors of the elementary reflectors. |
[out] | WORK | WORK is COMPLEX array, dimension (N) |
[out] | RWORK | RWORK is REAL array, dimension (2*N) |
[out] | INFO | INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value |
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. -- April 2011 -- For more details see LAPACK Working Note 176.
Definition at line 150 of file cgeqpf.f.