For the first step $t_1$,
only the initial condition at $t_0$ is available.
For the first step $t_1$,
only the initial condition at $t_0$ is available.
-\caption{The matrix-free\index{matrix-free} method for
- Krylov subspace\index{Krylov subspace} construction.}
+\caption{the matrix-free\index{matrix-free} method for
+ Krylov subspace\index{iterative method!Krylov subspace} construction}