song1st

參考網址:http://spreadsheetpage.com/index.php/tip/chart_trendline_formulas/

最近在分析資料時會需要用到EXCEL圖表產生的趨勢線(Trendline)，這功能很方便可以自動產出趨勢線的公式及誤差(R)，但是圖表產生的公式參數用VBA好像取不出來...(倒)
找到另一個近似的方法

Linear Trendline
Equation: y = m * x + b
m: =SLOPE(y,x)
b: =INTERCEPT(y,x)

Logarithmic Trendline
Equation: y = (c * LN(x)) + b
c: =INDEX(LINEST(y,LN(x)),1)
b: =INDEX(LINEST(y,LN(x)),1,2)

Power Trendline
Equation: y=c*x^b
c: =EXP(INDEX(LINEST(LN(y),LN(x),,),1,2))
b: =INDEX(LINEST(LN(y),LN(x),,),1)

Exponential Trendline
Equation: y = c *e ^(b * x)
c: =EXP(INDEX(LINEST(LN(y),x),1,2))
b: =INDEX(LINEST(LN(y),x),1)

2nd Order Polynomial Trendline
Equation: y = (c2 * x^2) + (c1 * x ^1) + b
c2: =INDEX(LINEST(y,x^{1,2}),1)
C1: =INDEX(LINEST(y,x^{1,2}),1,2)
b = =INDEX(LINEST(y,x^{1,2}),1,3)

3rd Order Polynomial Trendline
Equation: y = (c3 * x^3) + (c2 * x^2) + (c1 * x^1) + b
c3: =INDEX(LINEST(y,x^{1,2,3}),1)
c2: =INDEX(LINEST(y,x^{1,2,3}),1,2)
C1: =INDEX(LINEST(y,x^{1,2,3}),1,3)
b: =INDEX(LINEST(y,x^{1,2,3}),1,4)