Find the stability function for Runge's 4th order 4 stage method.
Implement RKF45. Solve
{y'(t)= y(t) +2t - 1
{y(0)=1
3{t E [0,1]
with step-length h E {1,1/2, 1/4, 1/8, 1/16, 1/32}
Plot the exact and estimated errors at the terminating point (t=1) vs. the step-length h on a log-log scale