vb 辛普森法求积分 我要具体能运行的代码

Private Sub Command1_Click()

Dim 下限 As Single, 上限 As Single, 允许误差 As Single, 实搜清际误差 As Single, 分条 As Integer

下限 = Val(InputBox("请输入积分下限"))

上限 = Val(InputBox("请输入积分上限"))

If 下限 >上限 Then

MsgBox "下限高于上限。怀疑输入手误。程序自册颤动交换"

t = 下限

下限 = 上限

上限 = t

End If

允许误差州漏败 = Val(InputBox("请输入允许误差"))

Print "积分下限："下限

Print "积分上限："上限

Print "允许误差为："允许误差

Print "积分结果为："积分(下限, 上限, 允许误差, 实际误差, 分条)

Print "划分梯形个数："分条

Print "截断误差为："实际误差

End Sub

Private Function 积分(下限 As Single, 上限 As Single, 误差要求 As Single, 误差 As Single, 块数 As Integer)

Dim p As Single

块数 = 2

积分值 = 0

步长 = (上限 - 下限) / 块数

p = 函数(下限) + 函数(上限)

d = 函数(下限 + 步长)

Do

s = (p + 4 * d) * 步长 / 3

误差 = Abs(s - 积分值)

If 误差 <= 误差要求 And 块数 >100 Then Exit Do

块数 = 块数 * 2

步长 = (上限 - 下限) / 块数

积分值 = s

p = p + 2 * d

d = 0

For i = 1 To 块数 - 1 Step 2

d = d + 函数(下限 + i * 步长)

Next i

Loop

积分 = s

End Function

Private Function 函数(自变量 As Single) '这个函数的内容是要你自己修改的

函数 = 自变量 * 自变量

End Function

Option Explicit

Private Sub form_Click()

Dim A As Integer, B As Integer, Step As Integer, Simp As Single

A = 0

B = 1

Step = 10000

Simp = simps(A, B, Step)

Print Simp

End Sub

Private Function Fun(X As Single) As Single

Fun = X ^ 3 * (1 - X) ^ 4

End Function

Private Function simps(A As Integer, B As Integer, Step As Integer) As Single

Dim H As Single, Four As Single, Two As Single, S As Single, X As Single, I As Integer

H = (B - A) / Step

X = A

S = Fun((A)) + Fun((B))

For I = 1 To Step / 2

X = X + H

Four = Four + Fun(X)

X = X + H

Two = Two + Fun(X)

Next I

Two = Two - Fun(X)

S = 4 * Four + 2 * Two

simps = S * H / 3

End Function

使用辛普森法求函数θ^3*(1-θ)^4在辩碰改区间【0~1】的定积分。

辛普森法求积分公式如吵知下：

y=h/3{f(a)+f(b)+4[f(a+h)+f(a+3h)+...+f(b-2h)]+2[f(a+2h)+f(a+4h)+...+f(b-h)]}

其中a、b为积分区间【a,b】,若将区间分为n（n为偶携判数)等份，则n越大，精度越高，h=(b-a)/n

---