For the latter approach, some additional notation is required. The techniques discussed here to approximate the true solution will do so by approximating y(t) only at a discrete set of points,
where the true solution that we seek exists for each t in some
specified interval
.
For simplicity, the methods discussed in subsequent sections will consider this discrete set of points to be equally spaced. Specifically
represents the ``step size'' that will be taken along the time axis. At
each point of this collection, an approximate solution is obtained, which
will be denoted by
In the sections which follow, methods which generate approximate solutions
are proposed and analyzed.