I think your question is poorly posed. Do you call the ODE solver using a syntax such as the following
[t, y] = ode23(odefun, tspan, y0)
whence ode23 returns a time point vector t that is not linearly spaced but you want them to be -- i.e., such that
all(diff(t)==t(2)-t(1))
In that case I recommend you read the documentation for ode23 more carefully. It is clearly documented how to do this. See either of
doc ode23
or
help ode23
