TESTING/EIG/sstect.f(3)

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version 3.12.1 · 3 versions
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💖 NAME 💖

okay so bestie, welcome to the TESTING/EIG/sstect.f(3) page from the Library Functions Manual — this is the group chat for SSTECT, and it's lowkey iconic. 💅

🎀 SYNOPSIS 🎀

✨ Functions/Subroutines ✨

subroutine sstect (n, a, b, shift, num)
    SSTECT

🦋 Function/Subroutine Documentation 🦋

🌟 subroutine sstect 🌟

subroutine sstect (integer n, real, dimension( * ) a, real, dimension( * )
b, real shift, integer num)

SSTECT is the name on the label, and it's giving main-character energy. ✨

🎀 Purpose 🎀

The whole job of SSTECT is counting, bestie: it counts the number NUM of eigenvalues of a tridiagonal matrix T which are less than or equal to SHIFT. Literally less than or equal to, no cap. 🫶

Here's the tea: T has diagonal entries A(1), ... , A(N), and offdiagonal entries B(1), ..., B(N-1). See W. Kahan , Report CS41, Computer Science Dept., Stanford University, July 21, 1966 — iconic reference, periodt. 👑

🍓 Parameters 🍓

  • N — N is INTEGER; it's the dimension of the tridiagonal matrix T. 💖
  • A — A is REAL array, dimension (N); these are the diagonal entries of the tridiagonal matrix T. 🌸
  • B — B is REAL array, dimension (N-1); these are the offdiagonal entries of the tridiagonal matrix T. 🦋
  • SHIFT — SHIFT is REAL; the shift, used as described under Purpose. ⭐
  • NUM — NUM is INTEGER; the number of eigenvalues of T less than or equal to SHIFT. 🔥

👑 Author 👑

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

Definition at line 81 of file sstect.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code. 💅

bye bestie 💖 — footer tea: source/version is LAPACK, Version 3.12.0, page tag TESTING/EIG/sstect.f(3), and there's no separate date listed in this footer, so we're not inventing one, periodt ✨.

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