Python查找函數f（x）=0根的解決方法

 　　這篇文章主要介紹了Python查找函數f(x)=0根的解決方法,涉及Python數學運算函數求解的相關技巧,需要的朋友可以參考下

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 ''' root = ridder(f,a,b,tol=1.0e-9). Finds a root of f(x) = 0 with Ridder's method. The root must be bracketed in (a,b). ''' import error from math import sqrt def ridder(f,a,b,tol=1.0e-9): fa = f(a) if fa == 0.0: return a fb = f(b) if fb == 0.0: return b if fa*fb > 0.0: error.err('Root is not bracketed') for i in range(30): # Compute the improved root x from Ridder's formula c = 0.5*(a + b); fc = f(c) s = sqrt(fc**2 - fa*fb) if s == 0.0: return None dx = (c - a)*fc/s if (fa - fb) < 0.0: dx = -dx x = c + dx; fx = f(x) # Test for convergence if i > 0: if abs(x - xOld) < tol*max(abs(x),1.0): return x xOld = x # Re-bracket the root as tightly as possible if fc*fx > 0.0: if fa*fx < 0.0: b = x; fb = fx else: a = x; fa = fx else: a = c; b = x; fa = fc; fb = fx return None print 'Too many iterations'

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