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inv(x)=tan(x)-x
1 f. b( T0 U0 x- S逆函數(shù)可以 用表查 , 或是用牛頓法 $ L2 R. p0 O- q& l' H( q+ L
3 v2 n/ W; ^3 [2 Y; L, u! _$ I[vb6/vba] Office excel also with this moudle
$ L3 z1 N: u8 p; GPublic Function Inverse_inv(value As Variant)6 A; q2 m; _5 U- e
Dim ape As Double9 h! }1 b6 n8 L" U/ T7 K5 O! o
Dim pe0 As Double/ U% @, I1 X9 k1 T' u4 X# r) [
Dim pe1 As Double
# D* e- ?( [4 B, ^/ [ ape = (3 * value) ^ (1 / 3)
" K0 L( \& b& Z R) s* o/ F3 g5 F Do
& P' h1 m7 j) u0 p+ Y1 L- H If ape >= 1000000000# Then ape = PI / 2: Exit Do
) y3 t; o. g4 w pe0 = ape# H% m+ P, X* i4 r
pe1 = ape + (value + ape - Tan(ape)) / (Tan(ape) ^ 2)' Y! T4 K7 [; U+ W* k& m
ape = pe1$ \! N) m* Q- ] W3 @! B
Loop Until Abs(pe1 - pe0) <= 0.0000001
" F; a6 u: {4 G Inverse_inv = ape* _( l7 X/ q6 ]! T
End Function |
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樓主: 冰山
發(fā)表于 2010-5-19 18:24:40
