# slasq4.f - Man Page

## Synopsis

### Functions/Subroutines

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.

## Function/Subroutine Documentation

### 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:**

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

**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.

**Date:**June 2016

**Further Details:**

CNST1 = 9/16

Definition at line 153 of file slasq4.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page slasq4(3) is an alias of slasq4.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK