东北石油大学计算方法上机实验答案.doc

《东北石油大学计算方法上机实验答案.doc》由会员分享，可在线阅读，更多相关《东北石油大学计算方法上机实验答案.doc（8页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、【精品文档】如有侵权，请联系网站删除，仅供学习与交流东北石油大学计算方法上机实验答案.精品文档.实验一1.Private Function f(x!) f=x3-2*x2-4*x-7End FunctionPrivate Sub form_click()Dim a!, b!, x!, c!a = 3: b = 4Do While Abs(b - a) 0.00001 c = (a + b) / 2 If f(c) = 0 Then Exit Do Else If f(a) * f(c) 0.00001 y = (a + b) / 2 If f(y) = 0 Then Exit Do Else

2、If f(a) * f(y) 0 Then b = y Else a = y End If End IfLoopg = yEnd FunctionPrivate Sub form_click()Dim a!, b!a = InputBox(输入隔根区间上界)b = InputBox(输入隔根区间下界)c = g(a, b)Print cEnd Sub2.Private Function f(x!)f = x 4 - 5 * x 2 + x + 2End FunctionPrivate Sub form_click()Dim a!, b!, c!, h!, x!, i%, j%, p(0 To

3、4) As Single, q(0 To 4) As Singlea = -6: b = 6: h = 0.3x = ai = 0For j = 0 To 100 If f(x) * f(x + h) 0.00001 c = (a + b) / 2 If f(c) = 0 Then Exit Do Else If f(a) * f(c) 0 Then b = c Else a = c End If End If Loop Print root=; c NextEnd Sub(h 取值 使得划分的隔根区间避开根所在得区间上下界）3.Private Sub form_click() Dim a(0

4、 To 20) As Single, y As Single, x As Single Dim i As Integer, n As Integer n = InputBox(输入多项式的次数) For i = 0 To n a(i) = InputBox(输入a( & Str(i) & ) Next i x = InputBox(输入x) y = a(n) For i = 1 To n y = y * x + a(n - i) Next i Print yEnd Sub实验二1.(1)Private Sub form_click()Dim x0 As Single, x1 As Single

5、Dim M As Integerx1 = 2: M = 5: k = 1Dox0 = x1x1 = x0 - (x0 3 - x0 2 - 2 * x0 - 3) / (3 * x0 2 - 2 * x0 - 2)k = k + 1Loop While k 0.00001Print x1End Sub(2)Private Sub form_click()Dim x0 As Single, x1 As SingleDim M As Integerx1 = 1: M = 6: k = 1Dox0 = x1x1 = x0 - (x0 - Sin(x0) - 0.5) / (1 - Cos(x0)k

6、= k + 1Loop While k 0.00001Print x1End Sub2Private Sub form_click()Dim x0 As Single, x1 As SingleDim a As Integera = InputBox(输入a)If a = 0 Then Print a的立方根=0 EndEnd Ifx1 = aDox0 = x1x1 = x0 - (x0 3 - a) / (3 * x0 2)Loop While Abs(x1 - x0) 0.000005Print a的立方根为：; x1End Sub3.Private Sub form_click()Dim

7、 x0 As Single, x1 As Single, x2 As SingleDim M As Integerx1 = 0: x2 = 1: M = 6: k = 1Dox0 = x1x1 = x2x2 = x1 - (f(x1) * (x1 - x0) / (f(x1) - f(x0)k = k + 1Loop While k 0.0001Print x1End SubPrivate Function f(x!)f = x + Sin(x) - 1End Function4.Private Sub form_click()Dim x#, x1#x1 = 1Dox = x1x1 = x -

8、 (x - Exp(-x) / (1 + Exp(-x)Loop While Abs(x1 - x) = 10 (-5)Print a的立方根为：; x1End Sub实验三1.按列选主元德高斯消去法解线性方程组的通用程序Option Base 1Private Sub Form_Click()Dim a(1 To 3, 1 To 4) As Single, t#, i!, j!, k!, r!, l#, x(1 To 3) As SingleFor i = 1 To 3 For j = 1 To 4 a(i, j) = InputBox(输入一个数) Print a(i, j); Next

9、j PrintNext iFor k = 1 To 2 r = k For i = k + 1 To 3 If Abs(a(i, k) Abs(a(r, k) Then r = i Next i If r k Then For i = 1 To 4 t = a(k, i) a(k, i) = a(r, i) a(r, i) = t Next i End If For i = k + 1 To 3 l = a(i, k) / a(k, k) For j = k + 1 To 4 a(i, j) = a(i, j) - l * a(k, j) Next j Next i Next k For k

10、= 3 To 1 Step -1 s = 0 For j = k + 1 To 3 s = s + a(k, j) * x(j) Next j x(k) = (a(k, 4) - s) / a(k, k) Next k For i = 1 To 3 Print x(i), Next iEnd Sub3.用LU分解法解线性方程组Private Sub form_click()Const n = 4Dim a(1 To n, 1 To n) As Single, l(1 To n, 1 To n) As Single, u(1 To n, 1 To n) As SingleDim x(1 To n

11、) As Single, y(1 To n) As Single, b(1 To n) As Single, s#, i!, j!, k!, r!For i = 1 To n For j = 1 To n a(i, j) = InputBox(输入a数组) Print a(i, j), Next j PrintNext iFor i = 1 To n b(i) = InputBox(输入b数组)Print b(i),Next iPrintFor k = 1 To n For j = k To n s = 0 For r = 1 To k - 1 s = s + l(k, r) * u(r, j

12、) Next r u(k, j) = a(k, j) - s Next j For i = k + 1 To n s = 0 For r = 1 To k - 1 s = s + l(i, r) * u(r, k) Next r l(i, k) = (a(i, k) - s) / u(k, k) Next i Next k For i = 1 To n s = 0 For k = 1 To i - 1 s = s + l(i, k) * y(k) Next k y(i) = b(i) - s Next i For i = n To 1 Step -1 s = 0 For k = i + 1 T

13、o n s = s + (u(i, k) * x(k) Next k x(i) = (y(i) - s) / u(i, i) Next i For i = 1 To n Print x(i) Next iEnd Sub实验四5.雅克比迭代Option Base 1Function cha(x!(), y!() As Single Dim z As Single, i As Single, k As Integer n = 3 z = Abs(x(1) - y(1) For i = 2 To n If z Abs(x(i) - y(i) Then z = Abs(x(i) - y(i) Next

14、 i cha = zEnd FunctionPrivate Sub form_click() Dim a1, x(3) As Single, y(3) As Single Dim t As Single, s As Single, a(3, 3) As Single Dim i As Integer, j As Integer, k As Integer, n As Integer n = 3 a1 = Array(10, -2, -1, -2, 10, -1, -1, -2, 5) b = Array(3, 15, 10) For i = 1 To n: y(i) = 0: Next i k

15、 = 1 For i = 1 To 3 For j = 1 To 3 a(i, j) = a1(k) k = k + 1 Next j, i For k = 1 To 30 For i = 1 To n x(i) = y(i) Next i For i = 1 To n t = 0 For j = 1 To n If i j Then t = t + a(i, j) * x(j) Next j y(i) = (b(i) - t) / a(i, i) Next i If cha(x, y) 30 Then Print 发散End Sub运行结果“19 1 2 3”Function函数是用来求（m

16、ax|y（i）-x（i）|）高斯赛德尔迭代Option Base 1Function cha(x!(), y!() As Single Dim z As Single, i As Single, k As Integer n = 3 z = Abs(x(1) - y(1) For i = 2 To n If z Abs(x(i) - y(i) Then z = Abs(x(i) - y(i) Next i cha = zEnd FunctionPrivate Sub form_click() Dim a1, x(3) As Single, y(3) As Single Dim t As Sin

17、gle, s As Single, a(3, 3) As Single Dim i As Integer, j As Integer, k As Integer, n As Integer n = 3 a1 = Array(10, -2, -1, -2, 10, -1, -1, -2, 5) b = Array(3, 15, 10) For i = 1 To n: x(i) = 0: Next i k = 1 For i = 1 To 3 For j = 1 To 3 a(i, j) = a1(k) k = k + 1 Next j, i For k = 1 To 30 For i = 1 T

18、o n y(i) = x(i) Next i For i = 1 To n t = 0 For j = 1 To n If i j Then t = t + a(i, j) * x(j) Next j x(i) = (b(i) - t) / a(i, i) Next i If cha(x, y) 30 Then Print 发散End Sub运行结果“11 1 2 3”注意比较雅克比迭代、高斯赛德尔迭代程序中“涂灰部分的区别”实验五3.拉格朗日插值多项式Private Sub Form_click()Const n = 3Dim p#, s!Dim x, y As Variantx = Arr

19、ay(1, 2, 3, 4)y = Array(4, 5, 14, 37)t = InputBox(input t) p = 0 For k = 0 To n s = 1 For i = 0 To n If i k Then s = s * (t - x(i) / (x(k) - x(i) End If Next i p = p + y(k) * s Next kPrint pEnd Sub运行结果（t=3.5）：23.375Vb牛顿基本插值公式程序Private Sub Form_click()Const n = 5Dim x(n) As Single, y(n) As Single, t#

20、, p#, s#For i = 0 To n x(i) = InputBox(input x & Trim(Str(i) y(i) = InputBox(input y & Trim(Str(i)Next it = InputBox(input t)For k = 1 To n For i = n To k Step -1 y(i) = (y(i) - y(i - 1) / (x(i) - x(i - k) Next iNext k p = y(0) h = 1For i = 1 To n h = h * (t - x(i - 1) p = p + h * y(i)Next iPrint p=

21、; pEnd Subi123456x(i)134526Y(i)2101726537运行结果（t=3.5）：13.25实验六曲线拟合Private Sub form_click()Dim l#, m#, n#, i%, j%, k%, t1# Dim x As Variant, y As Variantn = 7m = 2x = Array(0, 1, 2, 3, 4, 5, 6, 7)y = Array(0, 5, 3, 2, 1, 2, 4, 7)ReDim a(0 To m, 0 To m + 1) As Single, t(n) As SingleFor i = 0 To m s = 0

22、 For k = 1 To n s = s + (x(k) i) * y(k) Next k a(i, m + 1) = s For j = 0 To m s = 0 For k = 1 To n s = s + (x(k) (i + j) Next k a(i, j) = s Next j Next i For i = 0 To m For j = 0 To m + 1 Print a(i, j), Next j Print Next i For k = 0 To m r = k For i = k + 1 To m If Abs(a(i, k) Abs(a(r, k) Then r = i

23、 End If Next i If r k Then For i = 0 To m + 1 t1 = a(k, i) a(k, i) = a(r, i) a(r, i) = t1 Next i End If l = 1 For i = k + 1 To m l = a(i, k) / a(k, k) For j = k + 1 To m + 1 a(i, j) = a(i, j) - l * a(k, j) Next j Next i Next k For k = m To 0 Step -1 s = 0 For j = k + 1 To m s = s + a(k, j) * t(j) 注意

24、此处 Next j t(k) = (a(k, m + 1) - s) / a(k, k) Next k Print y=; t(0); For i = 1 To m If t(i) = 0 Then Print +; Print t(i); *x; i; Next iEnd Sub运行结果实验七1.编制变步长的梯形公式求数值积分的通用程序，试算积分为【积分下限为0，积分上限为1，被积函数为：1/（1+x*x）】当精度要求为0.00001时，计算结果为0.7853956.Private Sub form_click()Dim a As Single, b As Single, eps As Si

25、ngle, s As SingleDim x As Single, h As Single, t1 As Single, t As Singlea = InputBox(输入积分下限a)b = InputBox(输入积分上限b)eps = InputBox(输入精度要求eps)h = b - at2 = (h / 2) * (f(a) + f(b)Do t1 = t2 s = 0 For x = a + h / 2 To b Step h s = s + f(x) Next x t2 = t1 / 2 + (h / 2) * s h = h / 2 Loop While Abs(t1 - t2

26、) eps Print 积分的近似值：; t2End SubFunction f(x As Single) As Single f = 1 / (1 + x * x)End Function2.复合Simpson公式求积分的通用程序，设N=8，试算例题为积分下限为0，积分上限为1，被积函数为：1/（1+x*x），运行结果为0.785398Private Sub form_click()Dim a As Single, b As Single, eps As Single, s As SingleDim x As Single, h As Single, N As Singlea = Input

27、Box(输入积分下限a)b = InputBox(输入积分上限b)N = 8h = (b - a) / (2 * N)s = f(a)x = aFor i = 1 To Nx = x + hs = s + 4 * f(x)x = x + hs = s + 2 * f(x)Next is = (h / 3) * (s - f(b)Print sEnd SubFunction f(x As Single) As Single f = 1 / (1 + x * x)End Function3.编制龙贝格积分公式求数值积分的通用程序，试算积分为【积分下限为0，积分上限为1，被积函数为：x * x *

28、Exp(x)】当精度要求为0.00001时，计算结果为0.7182818Function f!(x!) f = x * x * Exp(x)End FunctionPrivate Sub form_click()Dim a!, b!, h!, eps!, s!, t!(10, 10)Dim i%, j%, k% a = InputBox(输入积分下限) b = InputBox(输入积分上限) eps = InputBox(输入精度要求) k = 0 h = b - a t(0, 0) = (h / 2) * (f(a) + f(b) Do k = k + 1 h = h / 2 s = 0 For j = 1 To 2 (k - 1) s = s + f(a + (2 * j - 1) * h) Next j t(k, 0) = t(k - 1, 0) / 2 + h * s For i = 1 To k j = k - i t(j, i) = (4 i * t(j + 1, i - 1) - t(j, i - 1) / (4 i - 1) Next i Loop Until Abs(t(0, k) - t(0, k - 1) eps Print I=; t(0, k)End Sub