# scipy.optimize.fixed_point¶

scipy.optimize.fixed_point(func, x0, args=(), xtol=1e-08, maxiter=500, method='del2')[source]

Find a fixed point of the function.

Given a function of one or more variables and a starting point, find a fixed-point of the function: i.e. where func(x0) == x0.

Parameters: func : function Function to evaluate. x0 : array_like Fixed point of function. args : tuple, optional Extra arguments to func. xtol : float, optional Convergence tolerance, defaults to 1e-08. maxiter : int, optional Maximum number of iterations, defaults to 500. method : {“del2”, “iteration”}, optional Method of finding the fixed-point, defaults to “del2” which uses Steffensen’s Method with Aitken’s Del^2 convergence acceleration [R167]. The “iteration” method simply iterates the function until convergence is detected, without attempting to accelerate the convergence.

References

 [R167] (1, 2) Burden, Faires, “Numerical Analysis”, 5th edition, pg. 80

Examples

>>> from scipy import optimize
>>> def func(x, c1, c2):
...    return np.sqrt(c1/(x+c2))
>>> c1 = np.array([10,12.])
>>> c2 = np.array([3, 5.])
>>> optimize.fixed_point(func, [1.2, 1.3], args=(c1,c2))
array([ 1.4920333 ,  1.37228132])


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