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发表于 2010-6-8 17:53:09
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inv(x)=tan(x)-x* R5 N" s1 t! |6 ]: }+ c
逆函數可以 用表查 , 或是用牛頓法
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+ o5 J6 T+ E) i0 K[vb6/vba] Office excel also with this moudle 4 W9 k2 Q+ I6 j0 U
Public Function Inverse_inv(value As Variant)4 `( H, _; H9 p- r7 K
Dim ape As Double
3 h; X) T& O; n9 h' q' x a Dim pe0 As Double
7 |9 _; ^" C+ u1 c3 D" z Dim pe1 As Double5 ]9 T5 V1 W7 Z: ^' u
ape = (3 * value) ^ (1 / 3)- e% c$ }6 f3 s# Y! ]
Do. Q8 c& Q2 Y- b
If ape >= 1000000000# Then ape = PI / 2: Exit Do
a- V B$ A; l b' \ pe0 = ape8 R' x' M% R0 w" v t* Z8 T
pe1 = ape + (value + ape - Tan(ape)) / (Tan(ape) ^ 2)5 ], S* i* K" S; G* w
ape = pe1- F4 Z( z/ z3 |! N: G
Loop Until Abs(pe1 - pe0) <= 0.0000001
. G' s k b+ Z9 R. d8 D Inverse_inv = ape
/ W* g4 c( _% d7 q: ]End Function |
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