方法1.
#fun为指定的导数的函数
#rf4为四阶龙格库塔法
def fun(x,y):
f = y - (2 * x / y)
return f
#input
# x0,y0:初始给出的x0值，y0值
# h ：步长
# N ：迭代次数
#print
# x1,y1:每次迭代输出的结果
def rf4(x0,y0,h,N):
n = 1
while(n != N):
x1 = x0 + h
k1 = fun(x0, y0)
k2 = fun(x0+h/2, y0+h*k1/2)
k3 = fun(x0+h/2, y0+h*k2/2)
k4 = fun(x1, y0+h*k3)
y1 = y0 + h * (k1 + 2* k2 + 2 * k3 + k4) / 6
print("%.2f, %.6f" %(x1, y1))
n = n + 1
x0 = x1
y0 = y1
def main():
rf4(0,1,0.2,5)
main()
方法2.
https://blog.csdn.net/u012836279/article/details/80176985
