# 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 distributionI 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 symmetricalThank 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 functionPerfect, 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