Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?lasq4
Computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by ?bdsqr .
Syntax
call slasq4(i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g)
call dlasq4(i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g)
Include Files
mkl.fi
Description
The routine computes an approximation tau to the smallest eigenvalue using values of d from the previous transform.
Input Parameters
- i0
-
INTEGER . First index.
- n0
-
INTEGER . Last index.
- z
-
REAL for slasq4 DOUBLE PRECISION for dlasq4 . Array, DIMENSION (4 n ). z holds the qd array.
- pp
-
INTEGER . pp=0 for ping, pp=1 for pong.
- n0in
-
INTEGER . The value of n0 at start of eigtest .
- dmin
-
REAL for slasq4 DOUBLE PRECISION for dlasq4 . Minimum value of d .
- dmin1
-
REAL for slasq4 DOUBLE PRECISION for dlasq4 . Minimum value of d , excluding d ( n0 ).
- dmin2
-
REAL for slasq4 DOUBLE PRECISION for dlasq4 . Minimum value of d , excluding d ( n0 ) and d ( n0 -1).
- dn
-
REAL for slasq4 DOUBLE PRECISION for dlasq4 . Contains d(n).
- dn1
-
REAL for slasq4 DOUBLE PRECISION for dlasq4 . Contains d(n-1).
- dn2
-
REAL for slasq4 DOUBLE PRECISION for dlasq4 . Contains d(n-2).
- g
-
REAL for slasq4 DOUBLE PRECISION for dlasq4 . A scalar passed as an argument in order to save its value between calls to ?lasq4 .
Output Parameters
- tau
-
REAL for slasq4 DOUBLE PRECISION for dlasq4 . Shift.
- ttype
-
INTEGER . Shift type.
- g
-
REAL for slasq4 DOUBLE PRECISION for dlasq4 . A scalar passed as an argument in order to save its value between calls to ?lasq4 .