NAME

dlasq4 - DLASQ4 estimates TAU, the smallest eigenvalue of a matrix

SYNOPSIS

SUBROUTINE DLASQ4(
N, Q, E, TAU, SUP )

void dlasq4(long int n, double ∗q, double ∗e,
double ∗tau, double ∗sup)

INTEGER N

DOUBLE PRECISION SUP, TAU

DOUBLE PRECISION E( ∗ ), Q( ∗ )

PURPOSE

   DLASQ4 estimates TAU, the smallest eigenvalue of a matrix. This
   routine improves the input value of SUP which is an upper bound
   for the smallest eigenvalue for this matrix .
 

ARGUMENTS

N       (input) INTEGER
On entry, N specifies the number of rows and columns in the matrix. N must be at least 0.

Q       (input) DOUBLE PRECISION array, dimension (N)
Q array

E       (input) DOUBLE PRECISION array, dimension (N)
E array

TAU     (output) DOUBLE PRECISION
Estimate of the shift

SUP     (input/output) DOUBLE PRECISION
Upper bound for the smallest singular value

Sun, Inc.  —  Last change: 20 Sep 1996