Sufficient conditions are given so that the initial value problem
for the Shabat equation has a unique analytic solution, which,
together with its first derivative, converges absolutely for $z\in\mathbb{C}:|z| \lt T$ , $T \gt 0$ . Moreover, a bound of this solution
is given. The sufficient conditions involve only the initial
condition, the parameters of the equation, and $T$ . Furthermore,
from these conditions, one can obtain an upper bound for $T$ . Our
results are in consistence with some recently found results.