The secant method is an iterative root nding method that is super-linear. The method has the advantage that it is faster than linear methods and does not require knowledge of the derivative of the function whose root is desired. On the other hand, it requires two starting values. The secant method is dened by the recurrence relation:

Write a function root = secant(f,x₁,x₂,tol) that computes a root of the function with handle f using the starting values x1 and x2 to within the tolerance tol. The output root must satisfy abs(f(root))

Note: Your roots may dier slightly from those in the test cases, but should satisfy the specied tolerance. You are not allowed to use any of Matlab's builtin root nding functions.