SSVDCT(3)

📦 version 3.12.0, in opensuse-leap 16.0

🎀 NAME 🎀

okay so bestie, this is the page for SSVDCT, living in the Library Functions Manual — header-path vibes: /home/abui...IG/ssvdct.f(3). The actual source file is literally:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/EIG/ssvdct.f

🌸 SYNOPSIS 🌸

🫶 Functions/Subroutines 🫶

subroutine SSVDCT (n, s, e, shift, num)
    SSVDCT

💖 Function/Subroutine Documentation 💖

subroutine SSVDCT (integer n, real, dimension( * ) s, real, dimension( * ) e, real shift, integer num)
    SSVDCT

✨ Purpose ✨

okay so SSVDCT counts the number NUM of eigenvalues of a 2*N by 2*N tridiagonal matrix T which are less than or equal to SHIFT. T is formed by putting zeros on the diagonal and making the off-diagonals equal to S(1), E(1), S(2), E(2), ... , E(N-1), S(N).

If SHIFT is positive, NUM is equal to N plus the number of singular values of a bidiagonal matrix B less than or equal to SHIFT. Here B has diagonal entries S(1), ..., S(N) and superdiagonal entries E(1), ... E(N-1).

If SHIFT is negative, NUM is equal to the number of singular values of B greater than or equal to -SHIFT.

Also, the reference is: See W. Kahan , Report CS41, Computer Science Dept., Stanford University, July 21, 1966.

🎀 Parameters 🎀

  • N — N is INTEGER. The dimension of the bidiagonal matrix B.
  • S — S is REAL array, dimension (N). The diagonal entries of the bidiagonal matrix B.
  • E — E is REAL array of dimension (N-1). The superdiagonal entries of the bidiagonal matrix B.
  • 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 86 of file ssvdct.f.

💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code.

💖 and that's the whole page, bestie! Signed off with LAPACK Version 3.12.0 and the path /home/abui...IG/ssvdct.f(3) — now go be the main character of eigenvalue counting. periodt. 💖

📦 where this page comes from