pychebfun.py 文件源码

def dichotomy(self, f, kmin=2, kmax=12, raise_no_convergence=True,):
        """
        Compute the coefficients for a function f by dichotomy.
        kmin, kmax: log2 of number of interpolation points to try
        raise_no_convergence: whether to raise an exception if the dichotomy does not converge
        """

        for k in range(kmin, kmax):
            N = pow(2, k)

            sampled = self.sample_function(f, N)
            coeffs = self.polyfit(sampled)

            # 3) Check for negligible coefficients
            #    If within bound: get negligible coeffs and bread
            bnd = self._threshold(np.max(np.abs(coeffs)))

            last = abs(coeffs[-2:])
            if np.all(last <= bnd):
                break
        else:
            if raise_no_convergence:
                raise self.NoConvergence(last, bnd)
        return coeffs