The Gerdjikov-Ivanov (GI) system of q and r is defined by a quadratic
polynomial spectral problem with 2×2 matrix coefficients. Each element
of the matrix of n-fold Darboux transformation of this system is expressed by a
ratio of (n+1)×(n+1) determinant and n×n determinant of
eigenfunctions, which implies the determinant representation of q[n] and
r[n] generated from known solution q and r. By choosing some special
eigenvalues and eigenfunctions according to the reduction conditions
q[n]=−(r[n])∗, the determinant representation of q[n] provides
some new solutions of the GI equation. As examples, the breather solutions and
rogue wave of the GI is given explicitly by two-fold DT from a periodic "seed"
with a constant amplitude.Comment: 8 figures, 17 page