Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

ID 766686
Date 3/31/2023
Public

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?lasq6

Computes one dqd transform in ping-pong form. Used by ?bdsqr and ?stegr.

Syntax

call slasq6( i0, n0, z, pp, dmin, dmin1, dmin2, dn, dnm1, dnm2 )

call dlasq6( i0, n0, z, pp, dmin, dmin1, dmin2, dn, dnm1, dnm2 )

Include Files
  • mkl.fi
Description

The routine ?lasq6 computes one dqd (shift equal to zero) transform in ping-pong form, with protection against underflow and overflow.

Input Parameters
i0

INTEGER. First index.

n0

INTEGER. Last index.

z

REAL for slasq6

DOUBLE PRECISION for dlasq6.

Array, DIMENSION (4n). Z holds the qd array. emin is stored in z(4*n0) to avoid an extra argument.

pp

INTEGER. pp=0 for ping, pp=1 for pong.

Output Parameters
dmin

REAL for slasq6

DOUBLE PRECISION for dlasq6.

Minimum value of d.

dmin1

REAL for slasq6

DOUBLE PRECISION for dlasq6.

Minimum value of d, excluding d(n0).

dmin2

REAL for slasq6

DOUBLE PRECISION for dlasq6.

Minimum value of d, excluding d(n0) and d(n0-1).

dn

REAL for slasq6

DOUBLE PRECISION for dlasq6. Contains d(n0), the last value of d.

dnm1

REAL for slasq6

DOUBLE PRECISION for dlasq6. Contains d(n0-1).

dnm2

REAL for slasq6

DOUBLE PRECISION for dlasq6. Contains d(n0-2).