What are Numerical differentiation functions?

In the documentation for ODE15s, you describe the integration method as "NDFs" or "Numerical Differentiation Functions". Having tried to look these up both within the documentation and online I can't find an exact description of what they are but I need some idea of what to be researching for my project write-ups. Any help would be appreciated! Jon

[Jon Barnes-Nunn]

Thank you very much! Can I ask how you would normally get to this for future reference if I have similar problems?

Answer 1

[Walter Roberson]

https://www.mathworks.com/help/pdf_doc/otherdocs/ode_suite.pdf