插值法VB源程序

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一、線性插值應(yīng)用實(shí)例VB1

已知：169的平方根為13,196的平方根為14，編程求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=\EndSub

PrivateFunctionF(x,y,x0)

F=y(1)+(y(2)-y(1))/(x(2)-x(1))*(x0-x(1))EndFunction

線性插值應(yīng)用實(shí)例VB2

?已知水的溫度與密度和關(guān)系如下：

溫度密度

5.010.015.020.025.030.00.99

0.99

0.99

0.99

0.99990.997

試編程計(jì)算溫度為6、13、16、19、23、26oC時(shí)的密度。

PrivateSubCommand1_click()N=6

X=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.AddItem\x0\y0\

ForI=1To6X0=xc(I)Y0=f(N,X,Y,X0)

List1.AddItemStr$(X0)&Str$(Y0)NextIEndSub

PrivateFunctionf(N,X,Y,X0)ForI=1ToNIfX0=NThenW=N-1:EndIf

f=Y(W)+(Y(W+1)-Y(W))/(X(W+1)-X(W))*(X0-X(W))EndFunction

二、拉格朗日三點(diǎn)插值實(shí)例

例：試驗(yàn)測(cè)得25OC乙醇溶液的平均摩爾體積v與乙醇的摩爾分?jǐn)?shù)xi的關(guān)系數(shù)據(jù)如下表。試編程求摩爾數(shù)xi為0.3時(shí)的乙醇溶液的平均體積v。v21.2222.1623.1824.3225.5726.950.089

0.115

0.143

0.173

0.206

0.242

xi

vxi

28.4730.1532.0134.0736.370.281

0.323

0.369

0.420

0.477

VB清單

DimX,v

PrivateSubCommand1_click()

N=75

X=Array(0,8,7,6,5,4.8,4.6,4.4,4.4,4.0,3.8,3.6,3.4,3.2,3.0,2.9,2.8,2.7,2.6,2.5,2.4,2.00,1.95,1.90,1.85,1.80,1.75,1.70,1.68,1.66,1.64,1.62,1.60,1.58,1.56,1.54,1.52,1.50,1.48,1.46,1.44,1.42,1.40,1.39,1.38,1.37,1.36,1.35,1.34,1.33,1.32,1.31,1.30,1.29,1.28,1.27,1.26,1.25,1.24,1.23,1.22,1.21,1.20,1.19,1.18,1.17,1.16,1.15,1.14,1.13,1.12,1.11,1.10,1.09,1.08,1.07)

v=Array(0,0.24978,0.24970,0.24958,0.24937,0.24931,0.24925,0.24917,0.24907,0.24896,0.24883,0.24868,0.24849,0.24825,0.24795,0.24778,0.24758,0.24735,0.24708,0.24678,0.24643,0.24421,0.24380,0.24333,0.24281,0.24222,0.24156,0.24081,0.24048,0.24013,0.23977,0.23938,0.23897,0.23854,0.23807,0.23758,0.23705,0.23648,0.23588,0.23524,0.23455,0.23381,0.23301,0.23259,0.23215,0.23170,0.23123,0.23073,0.23022,0.22968,0.22912,0.22854,0.22893,0.22729,0.22662,0.22593,0.22520,0.22443,0.22361,0.22275,0.22185,0.22090,0.21990,0.21884,0.21771,0.21652,0.21526,0.21390,0.21245,0.21090,0.20923,0.20744,0.20549,0.20336,0.20234,0.19848)

M=3

X0=Val(Text1.Text)

IfX0X(N)ThenPrint\ElseEndIf

Callpt(N,M,X0,A,B)v0=F(X0,A,B)List1.AddItem\List1.AddItem\List1.AddItem\

List1.AddItem\EndSub

PrivateSubpt(N,M,X0,A,B)ForI=1ToNIfX0=NThenB=N:EndIfA=B-M+1EndSub

PrivateFunctionF(X0,A,B)ForI=AToBW=1ForJ=AToBIfJIThen

W=W*(X0-X(J))/(X(I)-X(J)):EndIfNextJ

s=s+W*v(I)NextIF=sEndFunction

三、拉格朗日全點(diǎn)插值VB

試對(duì)上例編程對(duì)比利用三個(gè)、五個(gè)、七個(gè)、九個(gè)和全部節(jié)點(diǎn)時(shí)，摩爾分?jǐn)?shù)xi為0.30時(shí)乙醇溶液的平均摩爾體積v。

DimX,v

PrivateSubCommand1_click()N=11

X=Array(0,0.0891,0.1153,0.1435,0.1739,0.2068,0.2424,0.2811,0.3234,0.3697,0.4207,0.4771)

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)ThenPrint\EndElseEndIf

List1.AddItem\ForM=3ToNStep2Callpt(N,M,X0,A,B)v0=F(X0,A,B)

List1.AddItem\A=\NextMEndSub

PrivateSubpt(N,M,X0,A,B)ForI=1ToNIfX0=NThenB=N:EndIfA=B-M+1EndSub

PrivateFunctionF(X0,A,B)ForI=AT