Series approximations to e to the x and ln x
Question
How would you approximate and numerically, and what can be said about the size of the error?
Short answer
Truncated Taylor series. with Lagrange remainder ; for , where for the alternating-series error is below the first omitted term . In practice one first reduces the argument (e.g. , ) so the series converges fast.
Adapted from Joshi, Denson & Downes, Quant Job Interview Questions and Answers, Q6.15, p.190; question and answer rewritten by SelfMadeQuant.com.
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