CUNGHR(3)

💖 CUNGHR(3) — Library Functions Manual 💖

okay bestie, welcome to CUNGHR(3), the LAPACK page that is literally all about generating a complex unitary matrix and looking iconic while doing it. No cap, this is some main-character linear algebra energy. ✨

💖 NAME 💖

The NAME section is just this path, periodt:

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

✨ SYNOPSIS ✨

Functions/Subroutines

   subroutine CUNGHR (n, ilo, ihi, a, lda, tau, work, lwork, info)
       CUNGHR

🌸 Function/Subroutine Documentation 🌸

   subroutine CUNGHR (integer n, integer ilo, integer ihi, complex, dimension(
       lda, * ) a, integer lda, complex, dimension( * ) tau, complex,
       dimension( * ) work, integer lwork, integer info)
       CUNGHR

🦋 Purpose 🦋

CUNGHR generates a complex unitary matrix Q which is defined as the product of IHI-ILO elementary reflectors of order N, as returned by CGEHRD:

Q = H(ilo) H(ilo+1) . . . H(ihi-1).

🎀 Parameters 🎀

• N — N is INTEGER; the order of the matrix Q. N >= 0.
• ILO — ILO is INTEGER.
• IHI — IHI is INTEGER. ILO and IHI must have the same values as in the previous call of CGEHRD. Q is equal to the unit matrix except in the submatrix Q(ilo+1:ihi,ilo+1:ihi). 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
• A — A is COMPLEX array, dimension (LDA,N). On entry, the vectors which define the elementary reflectors, as returned by CGEHRD. On exit, the N-by-N unitary matrix Q.
• LDA — LDA is INTEGER; the leading dimension of the array A. LDA >= max(1,N).
• TAU — TAU is COMPLEX array, dimension (N-1). TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by CGEHRD.
• WORK — WORK is COMPLEX array, dimension (MAX(1,LWORK)). On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
• LWORK — LWORK is INTEGER; the dimension of the array WORK. LWORK >= IHI-ILO. For optimum performance LWORK >= (IHI-ILO)*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.

Definition at line 125 of file cunghr.f.

🦋 Author 🦋

Generated automatically by Doxygen for LAPACK from the source code.

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sign-off era 🫶💅 the footer says LAPACK Version 3.12.0, and the source path vibe is /home/abui...RC/cunghr.f(3). The original page doesn't list a date, so I'm not inventing one — but that version/source combo is the whole footer moment. ✨