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ECE 6382. Pole and Product Expansions, Series Summation. D. R. Wilton ECE Dept. 8/24/10. Pole Expansion of Meromorphic Functions. Note that a pole at the origin is not allowed!.
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ECE 6382 Pole and Product Expansions, Series Summation D. R. Wilton ECE Dept. 8/24/10
Pole Expansion of Meromorphic Functions Note that a pole at the origin is not allowed! 1Historical note: It is often claimed that friction between Mittag-Leffler and Alfred Nobel resulted in there being no Nobel Prize in mathematics. However, it seems this is not likely the case; see, for example, www.snopes.com/science/nobel.asp
Example: Pole Expansion of cot z (cont.) • Actually, it isn’t necessary that the paths CN be circular; indeed it is simpler in this case to estimate the maximum value on a sequence of square paths of increasing size that pass between the poles
Example: Pole Expansion of cot z (cont.) coth (x) ―
Other Pole Expansions • The Mittag-Leffler theorem generalizes the partial fraction representation of a rational function to meromorphic functions
Useful Product Expansions • Product expansions generalize for entire functions the factorization of the numerator and denominator polynomials of a rational function into products of their roots
y C x … … -3 -2 -1 0 1 2 3 Summation of Series