用python程序編寫(xiě)公式，求大牛指點(diǎn)。

瑞安3980

附件中是一張圖片，圖片上邊是兩個(gè)與誤差平方和有關(guān)的公式，哪位大神能幫我把F和Obj用程序表示出來(lái)，感激不盡！

瑞安3980

icymirror

一個(gè)簡(jiǎn)單的例子，不過(guò)函數(shù)Calculate只對(duì)一個(gè)變量求導(dǎo)。

1. import sympy
   
2. 
   
3. def Calculate(function, factor, data):
   
4.     """
   
5.     Assumption:
   
6.         function is Sympy provided expression,
   
7.         factor is the symbol for diff,
   
8.         data is values in list
   
9.     """
   
10.     orig = function
    
11.     diffed = diff(function, factor)
    
12.     newSum = sum([(orig.evalf(subs={factor:item}) - diffed.evalf(subs={factor:item}))**2 for item in data])
    
13.     return (newSum/2, 1/newSum)
    
14. 
    
15. # Sample
    
16. a = Symbol("x")
    
17. newFunc = 3*a**2 + 7*a - 9
    
18. F,obj = Calculate(newFunc, a, range(10))

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