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AC-arctan(AC/80)*80=1是數(shù)學(xué)問(wèn)題。
2 B; \# A& G% K% N子子大俠既然讀過(guò)VB,那么讀VBA代碼就應(yīng)該沒(méi)什么困難,核心是數(shù)值計(jì)算。3 e! r3 \: s0 J3 S. r
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/ p% H) o( E9 {$ V3 A- T7 q" n定義待求解函數(shù):' G. e/ |) B" }
Public Function QesFun(ByVal Var_AC As Double) As Double" r3 u3 ]3 H' z' M7 ~
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QesFun = Var_AC - Atn(Var_AC / 80) * 80 - 15 |% Y% J6 L& Y+ Y0 g) n
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End Function
4 f* H( Y- T/ ^# I: i--------------------------------------------------------------------------------------------------
4 P: [: b4 z' j) p% J0 X1. 二分法
! D. A3 q7 f! S. @( C) Q. P1.1 由 Arctan(AC/80)=(AC-1)/80
5 h: R+ g& u" n 知 -PI()/2<(AC-1)/80< PI()/2. [, m/ g6 W; v* q/ ]% O
即 1 -80*PI()/2<AC<1+ 80*PI()/2+ c5 I6 k' N: J+ p
++++++++++++++++++++++++++++++++++++++
/ Q" _5 f8 c9 P1.2定義求解函數(shù):
9 ]8 i: r. e- }- lPublic Function SolFunDic(ByVal MaxLim As Double, ByVal MinLim As Double) As Double
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Dim Res#, VarAdj#
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VarAdj = 10 ^ -6/ |# P4 s" E+ M N
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If QesFun(MinLim + VarAdj) < QesFun(MaxLim - VarAdj) Then
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Do While (1)
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; S% |7 \3 _: S4 W Res = (MaxLim + MinLim) / 27 J9 B4 L3 u& |* h
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If Abs(QesFun(Res)) <= 10 ^ -12 Then
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' ~. s) r, K$ o6 e# `' x SolFunDic = Res: Exit Do+ e9 e8 k& w, x. d1 K3 f* L5 ~
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ElseIf (QesFun(Res) < 0) Then
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MinLim = Res1 V+ j. Y6 M/ y4 d) o
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" Y* l7 s' [- W4 `0 N9 ` MaxLim = Res, N2 K# U; B q- i+ K
/ j# y8 {3 N+ v; o, J! r End If8 p k* e1 P: [+ G9 g- h
- ^2 D% [7 \; G7 x6 N Loop
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Do While (1)" m2 H! f, I' W5 p2 R
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Res = (MaxLim + MinLim) / 2
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7 u0 P& I/ C" G4 e If Abs(QesFun(Res)) <= 10 ^ -12 Then
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SolFunDic = Res: Exit Do+ X* f2 H: l0 P% U% S% Y
$ V# i. R! b: [& N8 U2 l% ^ ElseIf (QesFun(Res) > 0) Then
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6 s' D A( e- V2 c! |+ \ MinLim = Res
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Else; ?5 i( ~: p Q' W7 N) R7 R
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MaxLim = Res
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/ W4 p7 p; j. [+ w End If1 ~& @% M7 m/ B' h& x% y+ ~
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End If/ `# ?4 z+ r( F* ^% T" n9 F, S
End Function* Q4 k6 M" `( E. o! n
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2. 牛頓法
. M; v( x% i8 t- f% U% B2.1 由 f(AC)=arctan(AC/80)*80+1-AC u. y- F8 V+ L0 z: |8 Z
求導(dǎo) f(AC)’=1/(1+(AC/80)^2)-1$ o$ [3 D4 N% u
即 AC_1=AC_0- f(AC)/ f(AC)’
3 ~; e& R4 K9 ?8 r( w--------------------------------------------------------------
" Z. m" Y. ]2 i; K0 t; ?2.2定義迭代函數(shù):; G. i1 h" o/ @8 u8 Z G3 t
Public Function QesFunNew(ByVal Var_AC As Double) As Double: {+ y; D$ k4 F R2 [9 g# q2 V
, n5 w4 h1 b% M0 K4 L7 C4 n QesFunNew = Var_AC - (Atn(Var_AC / 80) * 80 + 1 - Var_AC) / (1 / (1 + (Var_AC / 80) ^ 2) - 1)
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3 [' z8 h# Q6 h( V# M# iEnd Function5 V! n6 G! \) T* r R
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t: D$ X0 P' {* k. e4 k$ w! j2.3定義求解函數(shù): r& ^( W; q! z5 B N9 @! n
Public Function SolFunNew(ByVal IniAC As Double) As Double
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Dim Res#
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Do While (1), g1 i* Z( n" r7 ?1 V/ p
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Res = QesFunNew(IniAC)7 J- p. ]/ }2 d5 J
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If Abs(QesFun(Res)) <= 10 ^ -12 Then4 v6 E7 f: u0 }
5 z3 q- ]- r( F$ U SolFunNew = Res: Exit Do
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Else) Y' a1 @( I, h# N) A7 c# w4 A" b
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IniAC = Res- z5 W: e2 s; x& n; r" D, J
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Loop8 l) K+ L& d# V
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) c% D0 G+ w$ o/ a' S6 k: d t( ?" L7 `6 v這樣做可能有點(diǎn)麻煩,但涉及到循環(huán),迭代時(shí),可自由調(diào)用自定義VBA函數(shù)和工作表函數(shù)(矩陣計(jì)算連桿機(jī)構(gòu)),還可控制輸出表格,便于插圖。計(jì)算冷卻塔時(shí),積分得用辛普遜;解汽水比,得解非線性方程。對(duì)這些問(wèn)題,EXCEL 工作表自身好像很吃力。( r/ |& _" N0 J! o
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