• Help on Matlab code, if third part is too much, just first and second part is find too
• Write a function, which inputs a vector v and outputs a vector with the indices i which represent a sign change in v; i.e. report 15 if the sign changed in v between index 14 and index 15. Do not consider going from positive or negative to zero. One suggestion is to write conditions on the vector and some kind of shifted version of itself. This will be a local function.
• Then write the main function, that input two vectors representing the x and y coordinates of the graph of the function and will return a vector with the approximate indices of the local extrema and a vector with the approximate indices of the points of inflection.

• First have the function take the first derivative (approximately, see homework 2). Then use your local function to apply the first derivative test to see where the approximate local minima and maxima are.