线性方程组VB源程序.doc

第三章 线性方程组VB源程序1 简单迭代用简单迭代格式解下列方程组：VB源程序Private Sub Command1_Click()Dim n As IntegerDim a(), y(), g(), b(), x1(), x2()n = InputBox(方程维数)Dim i, j, k As IntegerReDim a(n + 1, n + 1), y(n + 1)ReDim g(n + 1), x1(n + 1), x2(n + 1), b(n + 1, n + 1)Dim s, eer, tk = 0For i = 1 To nx1(i) = 1x2(i) = 0Next iFor i = 1 To n For j = 1 To n Print i,j=; i, j a(i, j) = InputBox(a(i, j) Next j y(i) = InputBox(y(i)Next i For i = 1 To n g(i) = y(i) / a(i, i) Next iFor i = 1 To n For j = 1 To n If j = i Then b(i, j) = 0 Else b(i, j) = -a(i, j) / a(i, i) End If Next jNext i50 eer = 0For i = 1 To n eer = eer + Abs(x1(i) - x2(i)Next iIf eer 0.0001 Then GoTo 100Else For i = 1 To n x1(i) = x2(i) Next iEnd If For i = 1 To n s = 0 For j = 1 To n s = s + b(i, j) * x1(j) Next j x2(i) = s + g(i) Next ik = k + 1GoTo 50100For i = 1 To n Print x2(i)Next iPrint k=; kLabel1.Caption = x2(1)Label2.Caption = x2(2)End Sub1） 求解方程组启动上面的VB程序依次输入2，2，1，5，3，7，10，就可以得到方程的解。方程的解为： 2、紧凑迭代法VB清单例1：用紧凑迭代格式解方程组Private Sub Command1_Click()Dim i As Integer, j As IntegerDim y(), t(), x0(), x1(), kDim omigaDim s, b(), a(), eerDim n As Integern = InputBox(please enter n :)omiga = InputBox(omiga=)ReDim y(n), t(n), a(n, n), x0(n), x1(n), b(n, n)For i = 1 To nx0(i) = 0x1(i) = x0(i)Next iFor i = 1 To nFor j = 1 To nPrint i =; i, ; j = ; j; a(i, j) = InputBox(please enter a(i,j)Next jy(i) = InputBox(please enter y(j):)Next iFor i = 1 To nt(i) = y(i) / a(i, i)Next iFor i = 1 To nFor j = 1 To nIf j = i Thenb(i, j) = 0Elseb(i, j) = -a(i, j) / a(i, i)End IfNext jNext ik = 0Dok = k + 1For i = 1 To n s = 0 For j = 1 To n s = s + b(i, j) * x1(j) Next j x1(i) = s + t(i)s = s + t(i)x1(i) = (1 - omiga) * x0(i) + omiga * s Next ieer = 0For i = 1 To n eer = eer + Abs(x1(i) - x0(i)Next iFor i = 1 To n x0(i) = x1(i)Next iLoop Until eer = 0.001For i = 1 To nPrint x1(i)Next iPrint k=; kEnd Sub利用上面的程序，我们进行下面两组方程的计算，并和直接迭代法进行比较（精度和初值均相同）:方程组方法迭代次数X1X21直接120.999810.999811紧凑70.999520。999812直接40.2828000.1717002紧凑30.282830.171723、松弛迭代计算机算法该法的计算机迭代算法，和紧凑格式基本相同，所不同的是在计算x1(I)时作一修改即可，即只需将紧凑格式中的：x1(i)=s+t(i)改为：s = s + t(i)x1(i) = (1 - omiga) * x0(i) + omiga * s同时在初始化时增加omiga的定义及赋值工作即可。 4、高斯消去法VB清单Private Sub Command1_click()Dim i,j,m,n As IntegerDim a(),z(),x(),w n= InputBox(“n”)ReDim a(n+2,n+2),z(n+2,n+2),x(n+1)For I=1To n For j=1To n+1 a(I,j)=InputBox(a) Next jNext IFor I=1To n w=a(I,i) For j=1 To n+1 a(I,j)=a(I,j)/w Next jIf I= n Then GoTo 100For j=I+1 to n For k=I+1 To n+1 z(i,k)=a(I,k)*a(j,i) a(j,k)=a(j,k)-z(I,k) Next kNext jNext I100X(n+1)=0For k=n To 1 Step -1 s=0 Fo