 the coefficient of the quadratic term.

  B       (input) DOUBLE PRECISION
          The value of the coefficient of the linear term.

  C       (input) DOUBLE PRECISION
          The value of the coefficient of the constant term.

  Z1RE    (output) DOUBLE PRECISION
  Z1IM    (output) DOUBLE PRECISION
          The real and imaginary parts, respectively, of the largest
          root in magnitude.

  Z2RE    (output) DOUBLE PRECISION
  Z2IM    (output) DOUBLE PRECISION
          The real and imaginary par