SRC/sorgqr.f(3)

okay bestie, welcome to the SRC/sorgqr.f(3) page from the Library Functions Manual 💅 this is the SORGQR glow-up, and we are keeping every single detail. no cap.

🌸 NAME 🌸

SRC/sorgqr.f

🦋 SYNOPSIS 🦋

Functions/Subroutines

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

💖 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 it's defined as the first N columns of a product of K elementary reflectors of order M:

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

...as returned by SGEQRF. iconic behavior, honestly ✨

🍓 Parameters 🍓

• M — M is INTEGER. it's the number of rows of the matrix Q, and M >= 0.
• N — N is INTEGER. it's the number of columns of the matrix Q, and M >= N >= 0.
• K — K is INTEGER. it's the number of elementary reflectors whose product defines the matrix Q, and 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. main character transformation, fr fr.
• LDA — LDA is INTEGER. it's the first dimension of the array A, and 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 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. sneaky but legal 💅

• 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.

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that's the whole page, bestie — LAPACK Version 3.12.0, source SRC/sorgqr.f(3), and the auto-generated Doxygen credit is right there in the Author bit 🫶💜