f(x) f(x) ()=()( h true derivative forward finite divided difference approx. X X f(G,)=f)-f f(x)=)-f 2h f(x) h f(x) backward centered finite divided finite divided difference approx. difference approx. X 4f(x) x f(x) x f(x) x f(x) x true derivative forward finite divided difference approx. backward finite divided difference approx. centered finite divided difference approx.       h f x f x f x i i i  1        h f x f x f x i i i   1       h f x f x f x i i i 2 1  1  4