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AC-arctan(AC/80)*80=1是數(shù)學(xué)問(wèn)題。
; Z3 Y( `+ W7 k( Q1 m7 u# s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。
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定義待求解函數(shù):
; u. R3 ?7 E, T( b6 C8 OPublic Function QesFun(ByVal Var_AC As Double) As Double
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QesFun = Var_AC - Atn(Var_AC / 80) * 80 - 1
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% V4 F+ k" v/ A8 m! L, | l$ EEnd Function
6 `! J7 Y$ h$ \5 S: U8 ]; v6 q) N--------------------------------------------------------------------------------------------------
, b. t$ S$ e @0 I9 R7 g1. 二分法
: |6 ^9 a% H% m5 S# T1.1 由 Arctan(AC/80)=(AC-1)/803 G5 s2 r: ~# R5 p( k! |
知 -PI()/2<(AC-1)/80< PI()/2& Y. X* s+ r# [) Q
即 1 -80*PI()/2<AC<1+ 80*PI()/2. y' b O2 l& {) z9 _, x/ g
++++++++++++++++++++++++++++++++++++++! R: A: r6 s4 U9 E( j7 ]4 l8 [
1.2定義求解函數(shù):
" i# ?; k. A2 MPublic Function SolFunDic(ByVal MaxLim As Double, ByVal MinLim As Double) As Double6 `3 Z, p d8 Q/ I' c, ^
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Dim Res#, VarAdj#
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VarAdj = 10 ^ -6
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If QesFun(MinLim + VarAdj) < QesFun(MaxLim - VarAdj) Then2 U* T h0 J( \( A
, ?* O: k, ?" d! c1 o Do While (1)+ Y; R ~8 u4 E$ e" N
/ v% K' e; B+ Q0 B: ? Res = (MaxLim + MinLim) / 2
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If Abs(QesFun(Res)) <= 10 ^ -12 Then
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SolFunDic = Res: Exit Do- v& W1 i5 G+ X Y/ V2 T$ D2 p. ~
1 o; }8 {0 O q; @+ i ElseIf (QesFun(Res) < 0) Then
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MinLim = Res
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Else
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MaxLim = Res
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! `8 s) s! Z- ~ H) X End If
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Loop
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Else
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; K M% B/ q* U: ] Do While (1)
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Res = (MaxLim + MinLim) / 2% y- k8 ^# [7 y3 l: X
3 ]- _* E: d' X9 C6 P& r( ? If Abs(QesFun(Res)) <= 10 ^ -12 Then+ \: S: M/ G; I1 I3 d0 o& W
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SolFunDic = Res: Exit Do5 i5 a: `+ V* _. o
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ElseIf (QesFun(Res) > 0) Then
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MinLim = Res( K3 {6 t& n6 R; R" ]
' S2 ?* K B' |% f* u Else
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MaxLim = Res1 b0 R# P. y) o) k" r# z
8 R5 G9 q! s1 D. Q- }# M5 R0 k1 {$ { End If! ?. A% g6 S! h: ], O. O
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Loop- n1 x* p2 }2 Y. e; Q& w) W6 E
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End Function! E8 \& G4 T/ C7 j7 X( c4 [- n; g
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/ p2 V( u1 I4 Y4 z9 d2. 牛頓法
7 @' A' k- O4 A5 E# t2.1 由 f(AC)=arctan(AC/80)*80+1-AC
" V& a$ s, \1 S' N% a; @, _ 求導(dǎo) f(AC)’=1/(1+(AC/80)^2)-1
! |/ W0 W# i; j& }9 A3 S: t! M" q- x 即 AC_1=AC_0- f(AC)/ f(AC)’5 s1 @; t; {, |" @
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) W3 e# }2 V, ~! E( d2.2定義迭代函數(shù):
( U+ }$ C" l. l( j/ xPublic Function QesFunNew(ByVal Var_AC As Double) As Double
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QesFunNew = Var_AC - (Atn(Var_AC / 80) * 80 + 1 - Var_AC) / (1 / (1 + (Var_AC / 80) ^ 2) - 1)9 \4 i! W3 I5 I2 A- g
1 Y$ ?8 |/ T0 [0 C+ [End Function
8 e1 A4 F* N+ j; ^, a---------------------------------------------------------------
4 _0 M S2 _& H! N+ Z2.3定義求解函數(shù)) t/ G% u" U: M$ |: p
Public Function SolFunNew(ByVal IniAC As Double) As Double
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% b$ M2 K: z% v4 }Dim Res#
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Do While (1)
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Res = QesFunNew(IniAC)
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If Abs(QesFun(Res)) <= 10 ^ -12 Then8 }$ W) _6 J! r7 |$ E; u9 ]
4 U& \7 H6 {0 b0 T) I2 n SolFunNew = Res: Exit Do
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Else
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: g6 j V! r" I& a- I8 R IniAC = Res
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End If
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) o9 l: j/ `" _% B! L d* s0 x, kLoop
% {& v0 C$ ^/ U----------------------------------------------------------------------------------------------------------
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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,。
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