CHP5V4 Numerical Differentiation via Richardson Extrapolation

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In some cases you can also write f(x) as series using orthogonal polynomials on some interval [x0 - h, x0 + h]. The coefficients of chosen orthogonal polynomials are simply sums (sampled over the interval), and the derivative of the orthogonal series at x0 is easy to write. Richardson's extrapolation might use less computation in general though.