插值法VB源程序

1、第四章插值方法VB一、线性插值应用实例VB1、已知：169的平方根为13,196的平方根为14，编程求175的平方根PrivateSubCommand1_click()Dimx(1To2),y(1To2)AsSinglex(1)=169:y(1)=13x(2)=196:y(2)=14x0=175y0=F(x,y,x0)a=Format$(y0,#.#)Text1.Text=y0=&Str$(a)EndSubPrivateFunctionF(x,y,x0)F=y(1)+(y(2)-y(1)/(x(2)-x(1)*(x0-x(1)EndFunction线性插值应用实例VB2已知水的温度与密度和关系

2、如下：温度5.010.015.020.025.030.0密度0.99990.9970.990.990.990.99试编程计算温度为6、13、16、19、23、26oC时的密度。PrivateSubCommand1_click()N=6X=Array(0,5,10,15,20,25,30)Y=Array(0,0.999965,0.9997,0.999099,0.998203,0.997044,0.995646)xc=Array(0,6,13,16,19,23,26)List1.AddItemx0&y0ForI=1To6X0=xc(I)Y0=f(N,X,Y,X0)List1.AddItemStr$

3、(X0)&Str$(Y0)NextIEndSubPrivateFunctionf(N,X,Y,X0)ForI=1ToNIfX0=X(I)ThenW=IExitForEndIfNextIW=W-1IfW=NThenW=N-1:EndIff=Y(W)+(Y(W+1)-Y(W)/(X(W+1)-X(W)*(X0-X(W)EndFunction二、拉格朗日三点插值实例例：实验测得25OC乙醇溶液的平均摩尔体积v与乙醇的摩尔分数xi的关系数据如下表。试编程求摩尔数xi为0.3时的乙醇溶液的平均体积V。21.2222.1623.1824.3225.5726.950.0890.1150.1430.1730.

4、2060.242xi21.2222.1623.1824.3225.5726.950.0890.1150.1430.1730.2060.242xiv28.4730.1532.0134.0736.37v28.4730.1532.0134.0736.37xi0.2810.3230.3690.4200.477SitForml-|n|x|xi0.2810.3230.3690.4200.477SitForml-|n|x|拉格朗日三点插值VB清单DimX,vPrivateSubCommand1_click()N=75.95；1.90；1.85:X=Array(0,8；7,6,5,4.8；4.6,4.4,4.

5、4,4.0,3.8；3.6,3.4；3.2；3.0,2.9,2.&2.7；2.6；2.5；2.4；2.00；1,1.80,1.75,1.70,1.68,1.66,1.64,1.62,1.60,1.58；1.56,1.54,1.52；1.50；1.4&1.46；1.44；1.42；1.40；1.39；1.38,1.37,1.36,1.35,1.34,1.33,1.32,1.31,1.30,1.29,1.28,1.27,1.26,1.25,1.24,1.23,1.22,1.21,1.20,1.19,1.18；1.17；1.16；1.15；1.14；1.13；1.12；1.11；1.10；1.09；

6、1.08；1.07)v=Array(0；0.24978；0.24970；0.24958；0.24937；0.24931；0.24925；0.24917；0.24907；.95；1.90；1.85:0.24868；0.24849；0.24825；0.24795；0.24778；0.24758；0.24735；0.24708；0.24678；0.24643；0.24421；0.24380；0.24333；0.24281；0.24222；0.24156；0.24081；0.24048；0.24013；0.23977；0.23938；0.23897；0.23854；0.23807；0.23758；0.

7、23705；0.23648；0.23588；0.23524；0.23455；0.23381；0.23301；0.23259；0.23215；0.23170；0.23123；0.23073；0.23022；0.22968；0.22912；0.22854；0.22893；0.22729；0.22662；0.22593；0.22520；0.22443；0.22361；0.22275；0.22185；0.22090；0.21990；0.21884；0.21771；0.21652；0.21526；0.21390；0.21245；0.21090；0.20923；0.20744；0.20549；0.2033

8、6；0.20104；0.19848)M=3X0=Val(Text1.Text)IfX0X(N)ThenPrinterrorElseEndIfCallpt(N,M,X0,A,B)v0=F(X0,A,B)List1.AddItema=&AList1.AddItemb=&BList1.AddItemX0=&X0List1.AddItemv0=&Format$(v0,#.#)EndSubPrivateSubpt(N,M,X0,A,B)ForI=1ToNIfX0=X(I)ThenIfAbs(X0-X(I-1)=Abs(X0-X(I)ThenA=I-Int(M+1)/2)ExitForEndIfElseA

9、=I-Int(M/2)EndIfNextIIfA=NThenB=N:EndIfA=B-M+1EndSubPrivateFunctionF(X0,A,B)ForI=AToBW=1ForJ=AToBIfJIThenW=W*(X0-X(J)/(X(I)-X(J):EndIfNextJs=s+W*v(I)NextIF=sEndFunction三、拉格朗日全点插值VB试对上例编程对比利用三个、五个、七个、九个和全部节点时，摩尔分数xi为0.30时乙醇溶液的平均摩尔体积V。DimX,vPrivateSubCommand1_click()N=11X=Array(0,0.0891,0.1153,0.1435,

10、0.1739,0.2068,0.2424,0.2811,0.3234,0.3697,0.4207,0.4771)v=Array(0,21.22,22.16,23.18,24.32,25.57,26.95,28.47,30.15,32.01,34.07,36.37)X0=Val(Text1.Text)IfX0X(N)ThenPrinterrorEndElseEndIfList1.AddItemx0=&X0ForM=3ToNStep2Callpt(N,M,X0,A,B)v0=F(X0,A,B)List1.AddItemM=&M&A=&A&B=&B&v0&Format$(v0,#.#)NextMEndSubPrivateSubpt(N,M,X0,A,B)ForI=1ToNIfX0=X(I)ThenIfAbs(X0-X(I-1)=Abs(X0-X(I)ThenA=I-Int(M+1)/2)ExitForEndIfElseA=I-I