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发表于 2010-6-8 17:53:09
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inv(x)=tan(x)-x/ l; x: `( W' z/ B1 t
逆函數可以 用表查 , 或是用牛頓法
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1 a* {- [; F, l- v: g, G[vb6/vba] Office excel also with this moudle * s- A7 Q* [2 T& K1 t: I' \
Public Function Inverse_inv(value As Variant)9 Z& t- |2 n, _/ t! B/ A
Dim ape As Double A& x" R" t! g0 i
Dim pe0 As Double8 {2 H. Q0 l" x+ L9 O R) M
Dim pe1 As Double
/ r; y8 c- b7 m( p' \; \ ape = (3 * value) ^ (1 / 3)- G& }, W7 D' s: n# R8 [9 [
Do
" w V* f" L0 j6 y If ape >= 1000000000# Then ape = PI / 2: Exit Do
4 P% @8 h0 a$ B7 X" n pe0 = ape5 X% q7 w2 W, v( J* O: p1 @) u
pe1 = ape + (value + ape - Tan(ape)) / (Tan(ape) ^ 2)! X8 c( F' ?0 i* k3 n: K9 X5 q
ape = pe1
/ W: N3 M/ U) f$ U" P1 A Loop Until Abs(pe1 - pe0) <= 0.0000001
! N' }! t5 B: f2 V7 { p Inverse_inv = ape
# b7 P6 ~7 o0 AEnd Function |
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