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inv(x)=tan(x)-x
# o0 a5 I" p2 w% u0 @5 |逆函數可以 用表查 , 或是用牛頓法 / n/ \; L( h' v7 |+ X& N1 z
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[vb6/vba] Office excel also with this moudle
" \' O* _3 s- f8 T$ x$ [Public Function Inverse_inv(value As Variant)4 D9 \" \; m4 X' h
Dim ape As Double
. X/ F) @+ @) ? Dim pe0 As Double
2 E" N+ U4 V* Q' B9 d, t Dim pe1 As Double. T# [" L2 S( m1 O7 M% L' @4 ?
ape = (3 * value) ^ (1 / 3)
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If ape >= 1000000000# Then ape = PI / 2: Exit Do, }! r4 N/ y% ?1 s# k, {2 k
pe0 = ape
( ?, y/ ?7 F6 _) a* q pe1 = ape + (value + ape - Tan(ape)) / (Tan(ape) ^ 2)
5 K1 w8 {! _; B, S* I- x ape = pe1
' [: u3 l1 @; e1 q( x/ p Loop Until Abs(pe1 - pe0) <= 0.0000001
% C" z( k! B: ]1 p+ G Inverse_inv = ape
$ i7 x% D! r( M. B3 ~0 T5 ?6 fEnd Function |
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