83 SUBROUTINE sstect( N, A, B, SHIFT, NUM )
101 REAL ZERO, ONE, THREE
102 parameter ( zero = 0.0e0, one = 1.0e0, three = 3.0e0 )
106 REAL M1, M2, MX, OVFL, SOV, SSHIFT, SSUN, SUN, TMP,
114 INTRINSIC abs, max, sqrt
120 unfl = slamch(
'Safe minimum' )
121 ovfl = slamch(
'Overflow' )
127 mx = max( mx, abs( a( i+1 ) ), abs( b( i ) ) )
132 IF( shift.GE.three*mx )
THEN
136 IF( shift.LT.-three*mx )
THEN
159 sshift = ( shift*m1 )*m2
160 u = ( a( 1 )*m1 )*m2 - sshift
171 tmp = ( b( i-1 )*m1 )*m2
172 u = ( ( a( i )*m1 )*m2-tmp*( tmp / u ) ) - sshift
subroutine sstect(N, A, B, SHIFT, NUM)
SSTECT