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发表于 2010-6-8 17:53:09
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inv(x)=tan(x)-x) F8 T: @$ C& q% B% u. y2 y
逆函數可以 用表查 , 或是用牛頓法 9 H; y+ Q2 P) Y+ e
3 j) i" E4 g+ j0 q- [7 J
[vb6/vba] Office excel also with this moudle 0 p& o, Z* ?, ]5 w
Public Function Inverse_inv(value As Variant)" |7 X e( g3 b! B8 E4 B
Dim ape As Double
$ L) \; S" c3 L3 j! z% y Dim pe0 As Double5 q4 j; K" Q: U& v3 M: o; W2 C
Dim pe1 As Double
7 K( M4 v% q7 y1 \' ~) E& c ape = (3 * value) ^ (1 / 3)
! x- c& M' {4 X, v; G Do
( x0 u8 w5 p; W If ape >= 1000000000# Then ape = PI / 2: Exit Do
( x% w4 n; D$ x- Z0 M: N pe0 = ape
8 N( K$ Q% s- P r# b pe1 = ape + (value + ape - Tan(ape)) / (Tan(ape) ^ 2)+ X$ N2 P* L0 j+ l4 H$ |% _7 o, }
ape = pe1
& _" M1 k( ~3 T, }8 F& Y/ e Loop Until Abs(pe1 - pe0) <= 0.00000016 Z8 d& X0 i( ^! W2 _
Inverse_inv = ape! {3 M( w" {" U/ s+ ]
End Function |
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