VB牛顿迭代法、二分法和弦截法解一元三次方程.doc

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1、个人收集整理勿做商业用途VB牛顿迭代法、二分法和弦截法解一元三次方程。OptionExplicitPrivateaAsDouble，bAsDouble，cAsDouble,dAsDouble,xx1AsDouble，xx2AsDouble，eAsDoublePrivateSubForm_Load（)       a=1      ’a＊x^3+b*x^2+c＊x+d=0   b=2   c=3   d=—4   xx1=0    ’二分法区间或弦截法区间或牛顿迭代法初值   xx2=1    ’二分法区间或弦截法区间   e=0.00001’精度   

2、 EndSubPrivateSubCommand1_Click（）   ’牛顿迭代法       DimxAsDouble，yAsDouble，dyAsDouble，ydyAsDouble,iAsLong       x=xx1       Fori=0To1000       y=f(a,b,c,d，x）       dy=f1(a,b，c,x)       IfAbs（y）

3、tSub       ElseIfdy=0Then           Print"失败，请另设初值试试”           Print           ExitSub       EndIf       ydy=y/dy       x=x—ydy   Next       Print"失败！"   Print    EndSub个人收集整理，勿做商业用途个人收集整理勿做商业用途PrivateSubCommand2_Click（)   '二分法       Dimx1AsDouble，x2AsDouble，x0AsDouble，y1AsDoub

4、le,y2AsDouble,y0AsDouble，iAsLong       x1=xx1   x2=xx2   y1=f(a，b,c，d，x1)   y2=f（a，b，c，d,x2）       If（y1〉0Andy2>0）Or(y1〈0Andy2<0）Then       Print”y1="&y1&”y2="&y2&"，二分法里y1与y2不能同号,请重新设置x1和x2"   ElseIfy1=0Then       Print"二分法x="&x1       Print”迭代次数i=”&i   ElseIfy2=0Then       Prin

5、t"二分法x="&x2       Print”迭代次数i=”&i   Else               Fori=1To1000           x0=（x1+x2）/2           'Debug。Printx0           y0=f(a，b，c，d,x0)                       Ify0=0Then               Print"二分法x="＆x0               Print"迭代次数i=”&i               Print               ExitSub  

6、         ElseIfAbs(x1-x2）0Andy0>0）Then               x1=x0           Else               x2=x0           EndIf                   Next   

7、    Print”失败！"        个人收集整理勿做商业用途   EndIf   Print    EndSub文档为个人收集整理，来源于网络PrivateSubCommand3_Click（）   '弦截法       Dimx1AsDouble,x2AsDouble,x0AsDouble,y1AsDouble，y2AsDouble,y0AsDouble,iAsLong       x1=xx1   x2=xx2   y1=f（a,b，c，d，x1）   y2=f(a,b，c，d，x2)       If(y1〉0Andy2〉0)Or(y1<

8、0Andy2<0）Then       Print"y1=”＆y1&”y2=”&y2＆"，二分