function [a,b,c,est]=rkf45b
c = [0 1/4  3/8  12/13  1  1/2]';
a = [zeros(1,6);1/4 zeros(1,5);3/32 9/32 zeros(1,4);
    1932/2197 -7200/2197 7296/2197 0 0 0;439/216 -8 3680/513 -845/4104 0 0;
    -8/27 2 -3544/2565 1859/4104 -11/40 0];
b = [16/135 0 6656/12825 28561/56430 -9/50 2/55]';
est = [-1/360 0 128/4275 2197/75240 -1/50 -2/55]';