lasq4(3)

📦
version 3.12.1 · 9 versions
, in arch rolling

💖 NAME 💖

okay so this is the lasq4(3) page from the Library Functions Manual, and we're doing the dqds step together, bestie. The actual name situation is:

lasq4 — lasq4: dqds step.

That's it. That's the name. Iconic. 🎀

✨ SYNOPSIS ✨

💖 Functions

🦋 subroutine dlasq4

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.

🦋 subroutine slasq4

subroutine slasq4 (i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1,
    dn2, tau, ttype, g)

SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.

🌸 DETAILED DESCRIPTION 🌸

This is Doxygen-generated LAPACK documentation, so the detailed description energy lives in the function docs right below. We are not skipping a single parameter, promise. 🫶

🎀 FUNCTION DOCUMENTATION 🎀

💅 subroutine dlasq4

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

The whole point is this, bestie: DLASQ4 computes an approximation TAU to the smallest eigenvalue using values of d from the previous transform. It's used by sbdsqr. Slay. 💜

🌈 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

Further Details: CNST1 = 9/16

Definition at line 149 of file dlasq4.f.

💅 subroutine slasq4

subroutine slasq4 (integer i0, integer n0, real, dimension( * ) z, integer pp, integer n0in, real dmin, real dmin1, real dmin2, real dn, real dn1, real dn2, real tau, integer ttype, real g)

SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.

✨ Purpose

Same main-character assignment, just the REAL version: SLASQ4 computes an approximation TAU to the smallest eigenvalue using values of d from the previous transform. It's used by sbdsqr. Periodt. 🦋

🌈 Parameters

  • I0 — I0 is INTEGER; first index.
  • N0 — N0 is INTEGER; last index.
  • Z — Z is REAL 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 REAL; minimum value of d.
  • DMIN1 — DMIN1 is REAL; minimum value of d, excluding D( N0 ).
  • DMIN2 — DMIN2 is REAL; minimum value of d, excluding D( N0 ) and D( N0-1 ).
  • DN — DN is REAL; d(N).
  • DN1 — DN1 is REAL; d(N-1).
  • DN2 — DN2 is REAL; d(N-2).
  • TAU — TAU is REAL; this is the shift.
  • TTYPE — TTYPE is INTEGER; shift type.
  • G — G is REAL; G is passed as an argument in order to save its value between calls to SLASQ4.

👑 Author

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

🧚 Further Details

Further Details: CNST1 = 9/16

Definition at line 149 of file slasq4.f.

👑 AUTHOR 👑

Generated automatically by Doxygen for LAPACK from the source code.

💖 So that's the whole lasq4(3) situation: LAPACK Version 3.12.0, page lasq4(3), footer sign-off delivered with maximum sparkle. Mwah. 🎀✨

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