How to write a function to calculate ODE?

Write a function which for a given value of the time, current population and growth rate returns the value of the derivative for an exponential growth model:

dN/dt = rN

No idea where to start.

Answer 1

[madhan ravi]

Start by reading this documentation page

Answer 2

[Torsten]

Solve the ODE using Euler's method, e.g., and - instead of returning the solution N - return r*N.