释义 |
Schwarz's Inequality
 | (1) |
Written out explicitly
 | (2) |
with equality Iff with a constant. To derive, let be aComplex function and a Complex constant such that for some and . Since ,
 | (3) |
with equality when . Set
 | (4) |
so that
 | (5) |
Plugging (5) and (4) into (3) then gives | |  | (6) |
 | (7) |
 | (8) |
so
 | (9) |
Bessel's Inequality can be derived from this. ReferencesAbramowitz, M. and Stegun, C. A. (Eds.). Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, 9th printing. New York: Dover, p. 11, 1972.Arfken, G. Mathematical Methods for Physicists, 3rd ed. Orlando, FL: Academic Press, pp. 527-529, 1985.
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