LASQ4 - 5.2 English - 68552

AOCL API Guide (68552)

Document ID
68552
Release Date
2025-12-29
Version
5.2 English
template<typename T>
void lasq4(integer *i0, integer *n0, T *z, integer *pp, integer *n0in, T *dmin, T *dmin1, T *dmin2, T *dn, T *dn1, T *dn2, T *tau, integer *ttype, T *g)#

LASQ4 computes an approximation to the smallest eigenvalue using

values of d from the previous transform. Used by sbdsqr.

Purpose:

 LASQ4 computes an approximation TAU to the smallest eigenvalue
 using values of d from the previous transform.
Parameters:
  • I0[in]

    I0 is INTEGER

    First index.

  • N0[in]

    N0 is INTEGER

    Last index.

  • Z[in]

    Z is REAL array, dimension (4*N0)

    Z holds the qd array.

  • PP[in]

    PP is INTEGER

    PP=0 for ping, PP=1 for pong.

  • N0IN[in]

    N0IN is INTEGER

    The value of N0 at start of EIGTEST.

  • DMIN[in]

    DMIN is REAL

    Minimum value of d.

  • DMIN1[in]

    DMIN1 is REAL

    Minimum value of d, excluding D(N0).

  • DMIN2[in]

    DMIN2 is REAL

    Minimum value of d, excluding D(N0) and D(N0-1).

  • DN[in]

    DN is REAL

    d(N)

  • DN1[in]

    DN1 is REAL

    d(N-1)

  • DN2[in]

    DN2 is REAL

    d(N-2)

  • TAU[out]

    TAU is REAL

    This is the shift.

  • TTYPE[out]

    TTYPE is INTEGER

    Shift type.

  • G[inout]

    G is REAL

    G is passed as an argument in order to save its value between calls to SLASQ4.