用VB做sin 函数。

用VB做sin 函数。

Function MySin(ByVal x As Double) As Double
Dim k As Integer
Dim nowSinx As Double

Dim temp As Double
Dim tol As Double
k = 1
tol = 0.00001
nowSinx = x
temp = x
Do
temp = -temp * (x * x) / (2 * k + 1) / (2 * k)
nowSinx = nowSinx + temp
k = k + 1
Loop While Abs(temp) > tol
MySin = nowSinx
End Function

'本程序改编自计算方法 C++作业。已在VB环境编译通过。
'可以用上一次计算的结果，没必要定义阶乘函数。
'MySin(2)结果是：0.909297.。。和Sin(2)差不多。

Function Sin(Number As Double) As Double
VBA.Math 的成员
返回一个角度的正弦值
不是有这个函数么....

Function MySin(x As Double) As Double
Dim t As Double, s As Double, n As Integer
't为连同符号的每项分母值连同符号 s为和值
t = 1: n = 1: s = 0
Do While Abs(x ^ n / t) >= 10 ^ (-5)
s = s + x ^ n / t
n = n + 2
t = (-1) ^ Int(n / 2) * JC(n)
'这里好好理解下
Loop
MySin = s
End Function
'定义阶乘函数
Function JC(n As Integer) As Long
If n <= 0 Then JC = 1: Exit Function
Dim i As Integer, t As Long
t = 1
For i = 1 To n
t = t * i
Next
JC = t
End Function
'这是自己写的sin函数 和系统的函数比较部分应该不用我说了吧

Function MySin(x!) As Double
Dim i%, m%, t!
m = 1
Do
MySin = MySin + t * (-1) ^ (m + 1)
t = 1
For i = 1 To 2 * m - 1
t = t * x / i
Next i
m = m + 1
Loop Until t < 10 ^ (-5)
End Function
最简单的写法。