How to find the derivative of y with respect to x (hard code derivative equation into the m-file, do not use symbolic toolbox)

My teacher has given me a task which is to plot the derivative of cost against x. Before I can plot the graph, I would need some way to find the gradient at each point in my graph. I am not allowed to use symbolic function and was told to hard code the derivative equation. Does anyone have any idea how to tackle this problem or perhaps provide me with a sample code? Thanks.

This is my code for plotting the graph of cost against x.

I have no idea how to start to find the gradient for all my x points on the curve.

Answer 1

[Geoff Hayes]

Jacky - if your cost equation is (with x the variable and D and L are constants)

f(x) = (2.5*10^6)*sqrt(D^2 + x^2) + (2.0*10^6)*(L - x);

then can't you just apply the chain rule to determine the derivative of f(x)?

[Jacky Foo]

Thanks for your reply, I will try that out.