np.polyfit:用多項式擬合一系列的數據點
np.polyfit(x, y, nums)
參數:nums表示多項式次數,nums=1相當於線性擬合
np.poly1d(np.ployfit(x,y, 1)):一維多項式類
>>> x = [1,2,3,4,5,6]
>>> y = [2.5,3.51,4.45,5.52,6.47,7.51]
>>> z1 = np.polyfit(x,y,1)
>>> p1 = np.poly1d(z1)
>>> print z1
[ 1. 1.49333333]
>>> print p1
1 x + 1.493
np.polyval:用多項式對象推斷下一個值
poly = np.polyfit(x, y, nums)
np.polyval(poly, x[-1] + 1)
np.roots:求多項式的根
poly = np.polyfit(x, y, nums)
np.roots(poly)
np.polyder:多項式函數求導(多項式求導仍然是一個多項式)
poly = np.polyfit(x, y, nums)
der = np.polyder(poly)
np.polysub:計算多項式的差
poly1 = np.polyfit(x1, y1, num1)
poly2 = np.polyfit(x2, y2, num2)
poly_sub = np.polysub(poly1, poly2)