lasq3(3)

📦
version 3.12.1 · 9 versions
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okay bestie, welcome to lasq3(3) from the Library Functions Manual — this is the dqds-step page and she is fully serving LAPACK realness. 💅✨

💖 NAME 💖

lasq3 — lasq3: dqds step

✨ SYNOPSIS ✨

🎀 Functions 🎀

  • subroutine dlasq3 (i0, n0, z, pp, dmin, sigma, desig, qmax, nfail, iter, ndiv, ieee, ttype, dmin1, dmin2, dn, dn1, dn2, g, tau) — DLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.
  • subroutine slasq3 (i0, n0, z, pp, dmin, sigma, desig, qmax, nfail, iter, ndiv, ieee, ttype, dmin1, dmin2, dn, dn1, dn2, g, tau) — SLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

🌸 DETAILED DESCRIPTION 🌸

okay so this section is literally just a heading in the original — no extra body text, no cap. 🦋

🔥 FUNCTION DOCUMENTATION 🔥

💜 subroutine dlasq3 💜

subroutine dlasq3 (integer i0, integer n0, double precision, dimension( * ) z, integer pp, double precision dmin, double precision sigma, double precision desig, double precision qmax, integer nfail, integer iter, integer ndiv, logical ieee, integer ttype, double precision dmin1, double precision dmin2, double precision dn, double precision dn1, double precision dn2, double precision g, double precision tau)

DLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

🎯 Purpose

DLASQ3 checks for deflation, computes a shift (TAU), and calls dqds. If something goes wrong, it changes shifts and tries again until the output is positive. periodt. 💅

🧚 Parameters

  • I0 — INTEGER. First index.
  • N0 — INTEGER. Last index.
  • Z — DOUBLE PRECISION array, dimension ( 4*N0 ). Z holds the qd array.
  • PP — INTEGER. PP=0 for ping, PP=1 for pong. PP=2 indicates that flipping was applied to the Z array and that the initial tests for deflation should not be performed.
  • DMIN — DOUBLE PRECISION. Minimum value of d.
  • SIGMA — DOUBLE PRECISION. Sum of shifts used in current segment.
  • DESIG — DOUBLE PRECISION. Lower order part of SIGMA.
  • QMAX — DOUBLE PRECISION. Maximum value of q.
  • NFAIL — INTEGER. Increment NFAIL by 1 each time the shift was too big.
  • ITER — INTEGER. Increment ITER by 1 for each iteration.
  • NDIV — INTEGER. Increment NDIV by 1 for each division.
  • IEEE — LOGICAL. Flag for IEEE or non IEEE arithmetic (passed to DLASQ5).
  • TTYPE — INTEGER. Shift type.
  • DMIN1 — DOUBLE PRECISION.
  • DMIN2 — DOUBLE PRECISION.
  • DN — DOUBLE PRECISION.
  • DN1 — DOUBLE PRECISION.
  • DN2 — DOUBLE PRECISION.
  • G — DOUBLE PRECISION.
  • TAU — DOUBLE PRECISION.

DMIN1, DMIN2, DN, DN1, DN2, G, and TAU are passed as arguments specifically to save their values between calls to DLASQ3. 🫶

👑 Author

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

📌 Definition

Definition at line 179 of file dlasq3.f.

💜 subroutine slasq3 💜

subroutine slasq3 (integer i0, integer n0, real, dimension( * ) z, integer pp, real dmin, real sigma, real desig, real qmax, integer nfail, integer iter, integer ndiv, logical ieee, integer ttype, real dmin1, real dmin2, real dn, real dn1, real dn2, real g, real tau)

SLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

🎯 Purpose

SLASQ3 checks for deflation, computes a shift (TAU), and calls dqds. If something goes wrong, it changes shifts and tries again until the output is positive. periodt. 💅

🧚 Parameters

  • I0 — INTEGER. First index.
  • N0 — INTEGER. Last index.
  • Z — REAL array, dimension ( 4*N0 ). Z holds the qd array.
  • PP — INTEGER. PP=0 for ping, PP=1 for pong. PP=2 indicates that flipping was applied to the Z array and that the initial tests for deflation should not be performed.
  • DMIN — REAL. Minimum value of d.
  • SIGMA — REAL. Sum of shifts used in current segment.
  • DESIG — REAL. Lower order part of SIGMA.
  • QMAX — REAL. Maximum value of q.
  • NFAIL — INTEGER. Increment NFAIL by 1 each time the shift was too big.
  • ITER — INTEGER. Increment ITER by 1 for each iteration.
  • NDIV — INTEGER. Increment NDIV by 1 for each division.
  • IEEE — LOGICAL. Flag for IEEE or non IEEE arithmetic (passed to SLASQ5).
  • TTYPE — INTEGER. Shift type.
  • DMIN1 — REAL.
  • DMIN2 — REAL.
  • DN — REAL.
  • DN1 — REAL.
  • DN2 — REAL.
  • G — REAL.
  • TAU — REAL.

DMIN1, DMIN2, DN, DN1, DN2, G, and TAU are passed as arguments specifically to save their values between calls to SLASQ3. 🫶

👑 Author

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

📌 Definition

Definition at line 179 of file slasq3.f.

👑 AUTHOR 👑

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