In the Secant method for finding real root of an equation, the graph of the function f(x) is approximated by code example
Example: secant method
x(i+1) = x(i-1)f(xi)-x(i)f(xi-1)/f(xi)-f(xi-1)
x(i+1) = x(i-1)f(xi)-x(i)f(xi-1)/f(xi)-f(xi-1)