How to find the derivative without using a symbolic function in Matlab?

Optimization problem using matlab?

• I have a problem for my final project, it's about shape design of multi segments rotating disk using matlab optimization toolbox. say if I have given input parameters Lmin, Lmax, L2, Lm, P2,Pm,(R2,...,Rm),N (all this parameters are known) where L, P, and R varies for each segments. and the required decision parameters are L3,..., Lm-1 (parameters which i must find the value) the constraints are Lmin ≤ Ln ≤ Lmax and σ radial(max) ≤ σ tangential(max) the formula for σ radial and σ tangential are known, which is a function of R, P, and L. the objective function is to minimize σ tangential (max). how i write this problem in matlab, which function I should use? I need to complete this problem as soon as possible. i would really appreciate any kind of help, i will gladly describe further information if necessary. and sorry for my bad grammar, English is not my native language. thank you very much

• Answer:

  Use calculus to minimize: in other words, set the derivative of " σ tangential (max)" equal to zero, then solve for σ . Matlab should be able to do that symbolically. If not, you'll need to use numeric methods, in which case you could write a program or script to step through discrete values σ , and repeat for smaller and smaller discrete values of dσ .