四阶龙格一库塔法 k1=f(t12y) h k2=∫(t1+,y2+k) 2 k3=f(1+,y+ h-2h2 k 4=f(t+h,yi+hk) h y+1=y1+(k1+2k2+2k3+k4)四阶龙格—库塔法 ( 2 2 ) 6 1 1 2 3 4 k k k k h y y i+ = i + + + + ( , ) 1 i i k = f t y ) 2 , 2 ( 2 1 k h y h k f t = i + i + y0 =        ) 2 , 2 ( 3 2 k h y h k f t = i + i + ( , ) 4 hk3 k f t h y = i + i +