Author: Panagiotis
27
Apr
In
[1, p. 34 exercise 2.13] we are asked to consider the problem of fitting the data
![\left\{x[0],...,x[N-1]\right\}](https://lysario.de/wp-content/cache/tex_9ceb2dd63d7268e57f2b85d862426d56.png)
by the sum of a dc signal and a sinusoid as:
![\hat{x}=\mu+A_c e^{j2\pi f_0n} \; n=0,1,...,N-1](https://lysario.de/wp-content/cache/tex_acb5556fb3038988a3c9cff6d859ca5b.png)
. The complex dc level
![\mu](https://lysario.de/wp-content/cache/tex_b5e8c0f01bda5443c359e91eff770e43.png)
and the sinusoidal amplitude
![A_c](https://lysario.de/wp-content/cache/tex_42c8d2e471fe149457eb04adfe323ae3.png)
are unknown and we are notified that we may view the determination of
![\mu](https://lysario.de/wp-content/cache/tex_b5e8c0f01bda5443c359e91eff770e43.png)
,
![A_c](https://lysario.de/wp-content/cache/tex_42c8d2e471fe149457eb04adfe323ae3.png)
as the solution of the overdetermined set of equations.
It is asked to find the least squares solution for
![\mu](https://lysario.de/wp-content/cache/tex_b5e8c0f01bda5443c359e91eff770e43.png)
and
![A_c](https://lysario.de/wp-content/cache/tex_42c8d2e471fe149457eb04adfe323ae3.png)
. If furthermore
![f_0=k/N](https://lysario.de/wp-content/cache/tex_6271253ad38c99ad8236514ba76d1ae7.png)
, where
![k](https://lysario.de/wp-content/cache/tex_8ce4b16b22b58894aa86c421e8759df3.png)
is a nonzero integer in the range
![[-N/2,N/2-1]](https://lysario.de/wp-content/cache/tex_3a5bf53d3e9902f7fffe9d68b2de1428.png)
for
![N](https://lysario.de/wp-content/cache/tex_8d9c307cb7f3c4a32822a51922d1ceaa.png)
even and
![[-(N-1)/2,(N-1)/2]](https://lysario.de/wp-content/cache/tex_dde8f99f860237fa0b573d2ad067620a.png)
for
![N](https://lysario.de/wp-content/cache/tex_8d9c307cb7f3c4a32822a51922d1ceaa.png)
odd we are asked to determine again the least squares solution.
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In
[1, p. 34 exercise 2.12] we are asked to verify the equations given for the Cholesky decomposition,
[1, (2.53)-(2.55)]. Furthermore it is requested to use these equations to find the inverse of the matrix given in problem
[1, 2.7].
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Author: Panagiotis
24
Jan
In
[1, p. 34 exercise 2.11] we are asked to find the eigenvalues of the circulant matrix given in
[1, (2.27),p.22].
read the conclusion >
In
[1, p. 34 exercise 2.10] it is asked to prove that if
![\mathbf{A}](https://lysario.de/wp-content/cache/tex_6c6404adc033dfed51422fdaf7fa0494.png)
is a complex
![n \times n](https://lysario.de/wp-content/cache/tex_50f17e5c11d610b19c0471830dc4dda1.png)
positive definite matrix and
![\mathbf{B}](https://lysario.de/wp-content/cache/tex_5d7c50a502fad9954c9b97f82d800c9f.png)
is a full rank complex
![m \times n](https://lysario.de/wp-content/cache/tex_fbfeb9c8459fee5a2bd529c07b881153.png)
matrix with
![m \leq n](https://lysario.de/wp-content/cache/tex_5d66e839723fd6f556c9bc51df0986e6.png)
, then
![\mathbf{BA}\mathbf{B}^H](https://lysario.de/wp-content/cache/tex_a68691d396d17eaeb814220f9dfde50c.png)
is also positive definite.
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In
[1, p. 34 exercise 2.9] we are asked to prove that the rank of the complex
![n\times n](https://lysario.de/wp-content/cache/tex_c60cbd704b15665c15d09ede0dc75a88.png)
matrix
where the
![\mathbf{u}_i](https://lysario.de/wp-content/cache/tex_702c7ec36a2e8896018332ba9b37e8cb.png)
are linearly independent complex
![n \times 1](https://lysario.de/wp-content/cache/tex_88512ab12706879fec83c0c3aa79931f.png)
vectors and the
![d_i](https://lysario.de/wp-content/cache/tex_d247f594c78d0d2be10fc6d82512cc4e.png)
‘s are real and positive, is equal to
![m](https://lysario.de/wp-content/cache/tex_6f8f57715090da2632453988d9a1501b.png)
if
![m \leq n](https://lysario.de/wp-content/cache/tex_098a604f6e66272c30bd5d1687b184bb.png)
. Furthermore we are asked what the rank equals to if
![m](https://lysario.de/wp-content/cache/tex_248e2dc408708ca5b502859348cab93f.png)
>
![n](https://lysario.de/wp-content/cache/tex_7b8b965ad4bca0e41ab51de7b31363a1.png)
.
read the conclusion >