Can't find all roots in Newtons-Raphson method (Python) -


the code using work fine 2 of 4 roots of function, can't seem make work 4 roots.

from numpy import * scipy import * import numpy np  def f(x):     return np.arctan(2*(x - 1)) - np.log(abs(x))  def fprime(x):     return (16/5)*((x - (5/4))**2)-1    def newtonraphson(x0,e=1.0e-3):     val in range(1, 15):         dx = - f(x0)/fprime(x0)         print(dx)         x0 = x0 + dx         if abs(dx) < e:              return x0,val     print('too many iterations\n')  root,numiter = newtonraphson(-1.0) print ('root =',root) print ('number of iterations =',numiter)

the roots should -0.300098, 0.425412, 1, 4.09946

when use -1.0, root -0.300098, , when use 1, root 1, can't seem other 2 roots. need code work? thanks

your code good, problem function - it's complicated method. can either use more sophisticated root finding method or can decrease dx , increase number of iterations. instance can use dx/1000 , 1.5 million maximum iterations. give roots. roots 1 , 4.0996 have use close guess. code works simple functions simple quadratic functions.


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