99 REAL cs, sigma, sn,
x, y
105 REAL negone, one, zero
106 parameter( negone = -1.0e0, one = 1.0e0, zero = 0.0e0 )
109 REAL r, s, thresh, w, z
121 IF( (sigma .EQ. zero .AND. abs(
x) .LT. thresh) .OR.
122 $ (abs(
x) .EQ. sigma .AND. y .EQ. zero) )
THEN
125 ELSE IF( sigma .EQ. zero )
THEN
126 IF(
x .GE. zero )
THEN
133 ELSE IF( abs(
x) .LT. thresh )
THEN
137 IF(
x .GE. zero )
THEN
142 z = s * (abs(
x)-sigma) * (s+sigma/
x)
151 CALL
slartgp( w, z, sn, cs, r )
REAL function slamch(CMACH)
SLAMCH
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...