SRC/cupgtr.f(3)

NAME ✨

SRC/cupgtr.f — okay so this is the SRC/cupgtr.f(3) page from the Library Functions Manual, and the main character is CUPGTR. That's the whole NAME section, bestie. 💅

SYNOPSIS 🎀

Functions/Subroutines

subroutine cupgtr (uplo, n, ap, tau, q, ldq, work, info)
    CUPGTR

Function/Subroutine Documentation 🌸

subroutine cupgtr (character uplo, integer n, complex, dimension( * ) ap,
    complex, dimension( * ) tau, complex, dimension( ldq, * ) q, integer
    ldq, complex, dimension( * ) work, integer info)
    CUPGTR

Purpose 💖

The way this works, bestie: CUPGTR generates a complex unitary matrix Q which is defined as the product of n-1 elementary reflectors H(i) of order n, as returned by CHPTRD using packed storage:

• if UPLO = 'U', Q = H(n-1) . . . H(2) H(1),
• if UPLO = 'L', Q = H(1) H(2) . . . H(n-1).

Parameters 🧚

UPLO

UPLO is CHARACTER*1

• = 'U': Upper triangular packed storage used in previous call to CHPTRD;
• = 'L': Lower triangular packed storage used in previous call to CHPTRD.

N

N is INTEGER

The order of the matrix Q. N >= 0.

AP

AP is COMPLEX array, dimension (N*(N+1)/2)

The vectors which define the elementary reflectors, as returned by CHPTRD.

TAU

TAU is COMPLEX array, dimension (N-1)

TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by CHPTRD.

Q

Q is COMPLEX array, dimension (LDQ,N)

The N-by-N unitary matrix Q.

LDQ

LDQ is INTEGER

The leading dimension of the array Q. LDQ >= max(1,N).

WORK

WORK is COMPLEX array, dimension (N-1)

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.

Definition at line 📍

Definition at line 113 of file cupgtr.f.

Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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💖 Signing off from LAPACK Version 3.12.0, page SRC/cupgtr.f(3) — the footer didn't give a date, so I'm not inventing one, bestie. 💅