mushin

Norway

Feb
17
awarded Tumbleweed
Feb
10
asked Method validation in non-regression problems
Dec
8
awarded Popular Question
Nov
9
comment Inproper model validation
$\hat{p}$ is estimated with 3 different models, so I want to know which model that is most accurate and overestimates most.
Nov
9
asked Inproper model validation
May
29
awarded Popular Question
Dec
4
awarded Notable Question
Nov
16
answered Fisher information of the Rayleigh distribution
Nov
16
comment Fisher information of the Rayleigh distribution
I did take them with respect to $x_{i}$'s. I will post the result asap.
Nov
16
asked Fisher information of the Rayleigh distribution
Sep
18
accepted Prove that a matrix is positive definite and symmetrical
Sep
18
comment Prove that a matrix is positive definite and symmetrical
Thank you. I will try to work something out. One thing that is certain is that $X^TX$ is symmetric, because $(X^TX)^T = X^T(X^T)^T = X^TX$. By the Spectral theorem, it follows that $X^TX$ can be decomposed into matrices of eigenvectors and eigenvalues. Now I should be able to show $v^TX^TXv \geq 0$ for all vectors v I think. And thank you Karl (below) for providing the hint of transpose of $X^TX$
Sep
17
asked Prove that a matrix is positive definite and symmetrical
Jul
2
awarded Curious
May
22
awarded Popular Question
May
7
comment Prove that the two integrals are equal with periodic function
Perfect, thank you. I need to work more with technical arguments like this rather than conceptual ones.
May
7
accepted Prove that the two integrals are equal with periodic function
May
6
asked Prove that the two integrals are equal with periodic function
May
3
awarded Yearling
May
3
awarded Yearling
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