DLARRC(3)

💅 DLARRC(3) — Library Functions Manual 💅

Straight from the Library Functions Manual, bestie: it's DLARRC(3), and she is literally here to count eigenvalues like it's her main character era. 💖

💖 NAME 💖

This page is for DLARRC(3), and its source-file baddie is /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dlarrc.f. Slay. ✨

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

Here's the synopsis, no cap — keep it exact:

subroutine DLARRC (jobt, n, vl, vu, d, e, pivmin, eigcnt, lcnt, rcnt,
    info)
    DLARRC computes the number of eigenvalues of the symmetric
    tridiagonal matrix.

🦋 Function/Subroutine Documentation 🦋

subroutine DLARRC (character jobt, integer n, double precision vl, double
    precision vu, double precision, dimension( * ) d, double precision,
    dimension( * ) e, double precision pivmin, integer eigcnt, integer lcnt,
    integer rcnt, integer info)

DLARRC computes the number of eigenvalues of the symmetric tridiagonal matrix. That's the whole assignment, and she ate. 💅

🎯 Purpose: 🎯

Bestie, the purpose is a whole vibe: find the number of eigenvalues of the symmetric tridiagonal matrix T that are in the interval (VL,VU] if JOBT = 'T', and of L D L^T if JOBT = 'L'. Periodt. 🌸

🌸 Parameters 🌸

• JOBT — JOBT is CHARACTER*1. It's the "which matrix are we doing?" selector: = 'T': Compute Sturm count for matrix T. = 'L': Compute Sturm count for matrix L D L^T.
• N — N is INTEGER. The order of the matrix. N > 0.
• VL — VL is DOUBLE PRECISION. The lower bound for the eigenvalues.
• VU — VU is DOUBLE PRECISION. The upper bound for the eigenvalues.
• D — D is DOUBLE PRECISION array, dimension (N). For JOBT = 'T': The N diagonal elements of the tridiagonal matrix T. For JOBT = 'L': The N diagonal elements of the diagonal matrix D.
• E — E is DOUBLE PRECISION array, dimension (N). For JOBT = 'T': The N-1 offdiagonal elements of the matrix T. For JOBT = 'L': The N-1 offdiagonal elements of the matrix L.
• PIVMIN — PIVMIN is DOUBLE PRECISION. The minimum pivot in the Sturm sequence for T.
• EIGCNT — EIGCNT is INTEGER. The number of eigenvalues of the symmetric tridiagonal matrix T that are in the interval (VL,VU].
• LCNT — LCNT is INTEGER.
• RCNT — RCNT is INTEGER. The left and right negcounts of the interval.
• INFO — INFO is INTEGER.

💖 Author 💖

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

🫶 Contributors: 🫶

• Beresford Parlett, University of California, Berkeley, USA
• Jim Demmel, University of California, Berkeley, USA
• Inderjit Dhillon, University of Texas, Austin, USA
• Osni Marques, LBNL/NERSC, USA
• Christof Voemel, University of California, Berkeley, USA

📌 Definition at line 135 of file dlarrc.f. 📌

That's where the magic is defined, bestie: line 135 of dlarrc.f. 💫

💫 Author 💫

Generated automatically by Doxygen for LAPACK from the source code.

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Okay bestie, that's the whole page 💖. This footer cutie is from LAPACK Version 3.12.0, with the path /home/abui...RC/dlarrc.f(3). Stay iconic, and may your eigenvalues always land in (VL,VU] ✨👑