Generalized hyperbolic functions, circulant matrices and functional equations

There is a contrast between the two sets of functional equations f 0 ( x + y ) = f 0 ( x ) f 0 ( y ) + f 1 ( x ) f 1 ( y ) , f 1 ( x + y ) = f 1 ( x ) f 0 ( y ) + f 0 ( x ) f 1 ( y ) , and f 0 ( x - y ) = f 0 ( x ) f 0 ( y ) - f 1 ( x ) f 1 ( y ) , f 1 ( x - y ) = f 1 ( x ) f 0 ( y ) - f 0 ( x ) f 1...

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Bibliographic Details
Published in:Linear algebra and its applications Vol. 406; pp. 272 - 284
Main Author: Muldoon, Martin E.
Format: Journal Article
Language:English
Published: New York, NY Elsevier Inc 01.09.2005
Elsevier Science
Subjects:
ISSN:0024-3795, 1873-1856
Online Access:Get full text
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Summary:There is a contrast between the two sets of functional equations f 0 ( x + y ) = f 0 ( x ) f 0 ( y ) + f 1 ( x ) f 1 ( y ) , f 1 ( x + y ) = f 1 ( x ) f 0 ( y ) + f 0 ( x ) f 1 ( y ) , and f 0 ( x - y ) = f 0 ( x ) f 0 ( y ) - f 1 ( x ) f 1 ( y ) , f 1 ( x - y ) = f 1 ( x ) f 0 ( y ) - f 0 ( x ) f 1 ( y ) satisfied by the even and odd components of a solution of f( x + y) = f( x) f( y). Schwaiger and, later, Förg-Rob and Schwaiger considered the extension of these ideas to the case where f is sum of n components. Here we shorten and simplify the statements and proofs of some of these results by a more systematic use of matrix notation.
ISSN:0024-3795
1873-1856
DOI:10.1016/j.laa.2005.04.011