94 REAL CS, SIGMA, SN, X, Y
100 REAL NEGONE, ONE, ZERO
101 parameter( negone = -1.0e0, one = 1.0e0, zero = 0.0e0 )
104 REAL R, S, THRESH, W, Z
119 IF( (sigma .EQ. zero .AND. abs(x) .LT. thresh) .OR.
120 $ (abs(x) .EQ. sigma .AND. y .EQ. zero) )
THEN
123 ELSE IF( sigma .EQ. zero )
THEN
124 IF( x .GE. zero )
THEN
131 ELSE IF( abs(x) .LT. thresh )
THEN
135 IF( x .GE. zero )
THEN
140 z = s * (abs(x)-sigma) * (s+sigma/x)
149 CALL slartgp( w, z, sn, cs, r )
subroutine slartgp(f, g, cs, sn, r)
SLARTGP generates a plane rotation so that the diagonal is nonnegative.
subroutine slartgs(x, y, sigma, cs, sn)
SLARTGS generates a plane rotation designed to introduce a bulge in implicit QR iteration for the bid...