标题: VB中定义Arccos函数 [打印本页] 作者: 游侠无极限 时间: 2003-4-18 01:11 标题: VB中定义Arccos函数 我是这样的： ! |) c( R& F) C) vPrivate Function Arccos(x As Double, n As Long)9 e0 ]) |( e5 y4 c8 B
Dim i As Long, y As Double - j: a2 C3 {: J6 N. ]& \1 lFor i = 1 To n , R+ g5 i) o. ~3 ~) u# t& f, M y = y + (-1 / Sqr(1 + (x / n * i) ^ 2)) * x / n2 C- ], I" ]. \/ U/ N" P1 D2 g
Next # D9 }& D g6 `( ]3 @9 NArccos = y2 u R c* u5 Z* a) m
End Function) _; X; e6 U# d J( {' G& n
( k& k+ Z$ c: i$ Y p用的是Arccos的微分来算近似值，怎么不对？ . y# R2 J6 ~# @, e# z& e% a作者: 煎饼 时间: 2003-4-19 22:04
公式对就没有问题拉作者: 游侠无极限 时间: 2003-4-24 22:58
Const pi As Double = 3.141592653595 |1 d: K* |- A) ^
Private Function Arccos(x As Double, n As Long) ' n 为函数精度，建议为100 5 o, i4 H/ j+ ~4 [: D Select Case x0 P& e0 l5 ` n/ w
Case 1+ k v1 J2 H' g$ }" z7 k
Arccos = 0 2 l! q( t5 S# {" P/ ?# K7 ^ Case -1 % ^/ g" G" F% r Arccos = pi" T: ~: C. ~% t5 G* F
Case -1 To 1- t8 O, F7 d, \4 q' h
Dim dx As Double, y As Double, i As Long1 \8 C9 }. e2 @7 e, S* t
dx = x / n5 V4 w) b$ k* Q1 y3 C
For i = 1 To n 0 o, q; U/ b/ w y = y + (-1 / Sqr(1 - (dx * i + dx / 2) ^ 2)) * dx ( c" ?& s+ j) _* H2 r: ?8 u Next ' G8 N* M% P; |# K" k Arccos = y + pi / 2 ; Q7 q2 t. R: P. ^ Case Else T+ j& o; j2 \% I9 m) L '异常# P: J; C: ^; h
End Select5 S/ l$ N9 @5 C* L% k
End Function ) G4 H5 D0 P2 g& ~$ A& B * M# e' Z+ y$ ?2 w) R8 s搞定了