SORGHR(3)

💅 SORGHR(3) — bestie, welcome to the Library Functions Manual ✨

okay so this is the whole vibe for SORGHR(3), and yes, it’s giving “LAPACK girlie who knows her reflectors.” 💖

🌸 NAME 🌸

The NAME section is literally just this source file path, no extra one-liner:

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

🦋 SYNOPSIS 🦋

🧚 Functions/Subroutines

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

💫 Function/Subroutine Documentation 💫

Here’s the full signature, bestie — character-for-character energy:

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

🎯 Purpose

okay so what does SORGHR actually do? It generates a real orthogonal matrix Q which is defined as the product of IHI-ILO elementary reflectors of order N, as returned by SGEHRD:

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

That’s the whole main-character job. 👑

🧸 Parameters

• N — INTEGER. The order of the matrix Q. N >= 0.
• ILO — INTEGER.
• IHI — INTEGER. ILO and IHI must have the same values as in the previous call of SGEHRD. 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 — REAL array, dimension (LDA,N). On entry, the vectors which define the elementary reflectors, as returned by SGEHRD. On exit, the N-by-N orthogonal matrix Q.
• LDA — INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• TAU — REAL array, dimension (N-1). TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGEHRD.
• WORK — REAL array, dimension (MAX(1,LWORK)). On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
• LWORK — 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 — INTEGER. = 0: successful exit. < 0: if INFO = -i, the i-th argument had an illegal value.

👑 Author 👑

The author squad on this one is:

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

Definition at line 125 of file sorghr.f.

🪄 Author 🪄

Generated automatically by Doxygen for LAPACK from the source code.

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That’s the whole page, bestie 💅✨ The footer says LAPACK Version 3.12.0 and points to /home/abui...RC/sorghr.f(3) — that’s the source/version tag, and there’s no date line on this one. 🫶