MATLAB: How to calculate the derivate of an equation

integrationnumerical integrationsignal processing

Hi All

I have the crack energy equation :

In which R and G are numbers , also c and m. N is loading cycle : so it's a signal.

in which rho is defined as :

Having the second equation, how can I derivate it with respect to N numerically ?

To calculate a numerical derivative of a vector, use the gradient function.

If ‘N’ is a vector, use gradient on it, then multiply that result by the other term in the

expression.

syms a theta(t) theta_prime f_prime
f(t) = a * cos(theta);
dtheta = diff(theta,t);
df = diff(f,t);
f_prime == subs(df, dtheta, theta_prime)

 Diff(y)./diff(x)