nag_zeros_quartic_real (c02alc) Example Program Results Roots of quartic equation Error estimates (machine-dependent) z = 2.00000 0.00000*i 3.38974e-15 z = -2.00000 0.00000*i 5.29396e-15 z = -1.00000 3.00000*i 4.54379e-15 z = -1.00000 -3.00000*i 4.54379e-15