# Question:How do I get the value of derivatives using dsolve/numeric in Maple?

## Question:How do I get the value of derivatives using dsolve/numeric in Maple?

Hi,

I recently have a problem when I try to use dsolve/numeric to solve an IVP. Suppose we have diff(y,x) = w(y) and y(0) =  y0. We can solve this IVP numerically by dsolve/numeric. In Matlab, we can obtain y and  the derivatives yp using the command [y,yp] = deval(sol,t) at any time t within the range we pre-defined. Basically, matlab ode solvers return a solution  skeleton first, then evaluate y and yp of the other points by a piecewise interpolation which is called by 'deval' command. So My question is: How can I do the same thing in Maple? I know maple also use interpolation to return a "continuous" solution.

To make it clear, I have the code here:

dsol8 := dsolve(dsys8, numeric, range=0..1,known=omega1,output=listprocedure,relerr=1*10^(-8));

The solution information is contained in dsol8. If we want to evaluate y(x) we can use

sol := eval(y(x), dsol8).

But how can I obtain the value of derivatives from dsol8? I tried  eval(diff(y(x),x), dsol8) which doesn't work. Any help will be appreciated, Thanks a lot!

^_^

Fei

﻿