SRC/dlasq4.f(3)

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version 3.12.1 · 7 versions
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💅 SRC/dlasq4.f(3) 💅

okay so this is the Library Functions Manual page for SRC/dlasq4.f(3) — manual name folded in right at the top, bestie, exactly as requested. Let’s get into the LAPACK lore. 🫶

✨ NAME ✨

SRC/dlasq4.f — that’s the name. Short, iconic, no notes. 🎀

🌸 SYNOPSIS 🌸

✨ Functions/Subroutines ✨

   subroutine dlasq4 (i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1,
       dn2, tau, ttype, g)

DLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr. 💖

🦋 Function/Subroutine Documentation 🦋

   subroutine dlasq4 (integer i0, integer n0, double precision, dimension( * )
       z, integer pp, integer n0in, double precision dmin, double precision
       dmin1, double precision dmin2, double precision dn, double precision
       dn1, double precision dn2, double precision tau, integer ttype, double
       precision g)

DLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr. 🌈

💖 Purpose 💖

DLASQ4 computes an approximation TAU to the smallest eigenvalue using values of d from the previous transform. That’s the whole purpose, and it ate. ✨

🎀 Parameters 🎀

  • I0 — I0 is INTEGER. First index. 🫶
  • N0 — N0 is INTEGER. Last index. 🫶
  • Z — Z is DOUBLE PRECISION array, dimension ( 4*N0 ). Z holds the qd array. 🦋
  • PP — PP is INTEGER. PP=0 for ping, PP=1 for pong. 💅
  • N0IN — N0IN is INTEGER. The value of N0 at start of EIGTEST. 🔥
  • DMIN — DMIN is DOUBLE PRECISION. Minimum value of d. 💖
  • DMIN1 — DMIN1 is DOUBLE PRECISION. Minimum value of d, excluding D( N0 ). 💖
  • DMIN2 — DMIN2 is DOUBLE PRECISION. Minimum value of d, excluding D( N0 ) and D( N0-1 ). 💖
  • DN — DN is DOUBLE PRECISION. d(N). 🎀
  • DN1 — DN1 is DOUBLE PRECISION. d(N-1). 🎀
  • DN2 — DN2 is DOUBLE PRECISION. d(N-2). 🎀
  • TAU — TAU is DOUBLE PRECISION. This is the shift. 👑
  • TTYPE — TTYPE is INTEGER. Shift type. ⭐
  • G — G is DOUBLE PRECISION. G is passed as an argument in order to save its value between calls to DLASQ4. 💜

👑 Author 👑

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

🔥 Further Details 🔥

CNST1 = 9/16

Definition at line 149 of file dlasq4.f. 📌

💀 Author 💀

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

okay final sign-off bestie: source LAPACK, version Version 3.12.0, page SRC/dlasq4.f(3) — mwah, slay, periodt. 💋💅

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