ZTZRZF(3)

🌸 NAME 🌸

Hey bestie! Welcome to the ZTZRZF(3) page in the Library Functions Manual — yes, you found the right one. 💅 This page is all about this file:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/ztzrzf.f

✨ SYNOPSIS ✨

Functions/Subroutines

       subroutine ZTZRZF (m, n, a, lda, tau, work, lwork, info)
           ZTZRZF

🦋 Function/Subroutine Documentation 🦋

   subroutine ZTZRZF (integer m, integer n, complex*16, dimension( lda, * ) a,
       integer lda, complex*16, dimension( * ) tau, complex*16, dimension( * )
       work, integer lwork, integer info)
       ZTZRZF

🎯 Purpose 🎯

Okay so here's the glow-up: ZTZRZF reduces the M-by-N (M<=N) complex upper trapezoidal matrix A to upper triangular form by means of unitary transformations. Periodt. 💖

The upper trapezoidal matrix A is factored as:

A = ( R  0 ) * Z,

where Z is an N-by-N unitary matrix and R is an M-by-M upper triangular matrix. That’s the whole assignment, bestie. ✨

🧸 Parameters 🧸

• M — M is INTEGER; this is the number of rows of the matrix A. M >= 0.
• N — N is INTEGER; this is the number of columns of the matrix A. N >= M.
• A — A is COMPLEX*16 array, dimension (LDA,N). On entry, the leading M-by-N upper trapezoidal part of the array A must contain the matrix to be factorized. On exit, the leading M-by-M upper triangular part of A contains the upper triangular matrix R, and elements M+1 to N of the first M rows of A, with the array TAU, represent the unitary matrix Z as a product of M elementary reflectors.
• LDA — LDA is INTEGER; this is the leading dimension of the array A. LDA >= max(1,M).
• TAU — TAU is COMPLEX*16 array, dimension (M); these are the scalar factors of the elementary reflectors.
• WORK — WORK is COMPLEX*16 array, dimension (MAX(1,LWORK)). On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
• LWORK — LWORK is INTEGER; this is the dimension of the array WORK. LWORK >= max(1,M). For optimum performance LWORK >= M*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 — 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.

🫶 Contributors 🫶

• A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA

🔥 Further Details 🔥

The N-by-N matrix Z can be computed by:

Z =  Z(1)*Z(2)* ... *Z(M)

where each N-by-N Z(k) is given by:

Z(k) = I - tau(k)*v(k)*v(k)**H

with v(k) is the kth row vector of the M-by-N matrix:

V = ( I   A(:,M+1:N) )

I is the M-by-M identity matrix, A(:,M+1:N) is the output stored in A on exit from ZTZRZF, and tau(k) is the kth element of the array TAU.

Definition at line 150 of file ztzrzf.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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💖 That’s the tea, fr fr: LAPACK Version 3.12.0, file /home/abui...RC/ztzrzf.f(3). Bye bestie — go slay those unitary transformations! 💅✨