释义 |
Contour IntegrationLet and be Polynomials of Degrees and withCoefficients , ..., and , ..., . Take the contour in the upper half-plane, replace by ,and write . Then
 | (1) |
Define a path which is straight along the Real axis from to and makes a circular arc to connect thetwo ends in the upper half of the Complex Plane. The Residue Theorem thengiveswhere Res denotes the Residues. Solving,
Define
and set
 | (4) |
then equation (3) becomes
 | (5) |
Now,
 | (6) |
for . That means that for , or , , so
 | (7) |
for . Apply Jordan's Lemma with . We must have
 | (8) |
so we require . Then
 | (9) |
for .
Since this must hold separately for Real and Imaginary Parts, this result can beextended to
 | (10) |
 | (11) |
It is also true that
 | (12) |
See also Cauchy Integral Formula, Cauchy Integral Theorem,Inside-Outside Theorem, Jordan's Lemma, Residue (Complex Analysis), Sine Integral References
Morse, P. M. and Feshbach, H. Methods of Theoretical Physics, Part I. New York: McGraw-Hill, pp. 353-356, 1953.
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