SORGQR(3)

🌈 sorgqr.f(3) — Library Functions Manual 🌈

okay so this is the glow-up of the SORGQR(3) page, bestie — manual name folded in right here so you don’t gotta squint at the header line: Library Functions Manual, file sorgqr.f(3). Now let’s get into the LAPACK tea 💅✨

🎀 NAME 🎀

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

---

✨ SYNOPSIS ✨

📚 Functions/Subroutines 📚

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

SORGQR — that’s the main character, no cap 👑

---

💖 Function/Subroutine Documentation 💖

subroutine SORGQR (integer m, integer n, integer k, real, dimension( lda, * ) a, integer lda, real, dimension( * ) tau, real, dimension( * ) work, integer lwork, integer info)

SORGQR

🌸 Purpose 🌸

okay so SORGQR generates an M-by-N real matrix Q with orthonormal columns, and Q is defined as the first N columns of a product of K elementary reflectors of order M — as returned by SGEQRF.

The formula is literally this iconic:

Q  =  H(1) H(2) . . . H(k)

🧸 Parameters 🧸

• M — M is INTEGER. It’s the number of rows of the matrix Q. You need M >= 0.
• N — N is INTEGER. It’s the number of columns of the matrix Q. You need M >= N >= 0.
• K — K is INTEGER. It’s the number of elementary reflectors whose product defines the matrix Q. You need N >= K >= 0.
• A — A is REAL array, dimension (LDA,N). On entry, the i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by SGEQRF in the first k columns of its array argument A. On exit, it’s the M-by-N matrix Q. glow-up complete 💫
• LDA — LDA is INTEGER. It’s the first dimension of the array A, and you need LDA >= max(1,M).
• TAU — TAU is REAL array, dimension (K). TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGEQRF.
• WORK — WORK is REAL array, dimension (MAX(1,LWORK)). On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
• LWORK — LWORK is INTEGER. It’s the dimension of the array WORK, and you need LWORK >= max(1,N). For optimum performance, LWORK >= N*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 has an illegal value.

👑 Author 👑

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

Definition at line 127 of file sorgqr.f.

🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code.

---

and that’s the whole page, bestie 🫶 — the footer says LAPACK Version 3.12.0 and points at /home/abui...RC/sorgqr.f(3). No date on that footer, so I’m not inventing one — just giving you the full vibe-checked manual 💖✨