词条 | Transfer matrix |
释义 |
In applied mathematics, the transfer matrix is a formulation in terms of a block-Toeplitz matrix of the two-scale equation, which characterizes refinable functions. Refinable functions play an important role in wavelet theory and finite element theory. For the mask , which is a vector with component indexes from to , the transfer matrix of , we call it here, is defined as More verbosely The effect of can be expressed in terms of the downsampling operator "": Properties
More precisely: Let be the even-indexed coefficients of () and let be the odd-indexed coefficients of (). Then , where is the resultant. This connection allows for fast computation using the Euclidean algorithm.
where denotes the mask with alternating signs, i.e. .
This is a concretion of the determinant property above. From the determinant property one knows that is singular whenever is singular. This property also tells, how vectors from the null space of can be converted to null space vectors of .
, then is an eigenvector of with respect to the same eigenvalue, i.e. .
Let be the periodization of with respect to period . That is is a circular filter, which means that the component indexes are residue classes with respect to the modulus . Then with the upsampling operator it holds Actually not convolutions are necessary, but only ones, when applying the strategy of efficient computation of powers. Even more the approach can be further sped up using the Fast Fourier transform.
where is the size of the filter and if all eigenvalues are real, it is also true that , where . See also
References
|first=Gilbert|last=Strang |author-link=Gilbert Strang |title=Eigenvalues of and convergence of the cascade algorithm |journal=IEEE Transactions on Signal Processing |volume=44 |pages=233–238 |year=1996 }}
|first=Henning |last=Thielemann |url=http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000103131 |title=Optimally matched wavelets |type=PhD thesis |year=2006 }} (contains proofs of the above properties) 2 : Wavelets|Numerical analysis |
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