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 Apr 10 asked Integral calculating involving Gaussian norm Feb 8 awarded Notable Question Feb 1 awarded Notable Question Dec 28 awarded Notable Question Oct 27 accepted Find the angle of complex number Oct 27 asked Find the angle of complex number Oct 20 comment Find a function by its Fourier coefficients Yes. $x[n]$ is the extension one. Oct 20 asked Find a function by its Fourier coefficients Oct 11 comment How to differentiate $(y-X\beta)^T(y-X\beta)$ w.r.t. $\beta$ and useful formulas in this context? Thanks for the answer but the textbook answer is $-2X^T(y-X\beta)$. Shouldn't I use $\partial f / \partial \beta = \nabla f$? Oct 11 revised How to differentiate $(y-X\beta)^T(y-X\beta)$ w.r.t. $\beta$ and useful formulas in this context? added 65 characters in body Oct 11 asked How to differentiate $(y-X\beta)^T(y-X\beta)$ w.r.t. $\beta$ and useful formulas in this context? Sep 20 awarded Yearling Aug 3 awarded Popular Question Jun 22 revised How to prove rigorously $L[\delta(t-a)] = e^{-as}$? added 117 characters in body Jun 22 asked How to prove rigorously $L[\delta(t-a)] = e^{-as}$? Jun 18 asked Find $f(1)$ given the following ($f$ polynomial) Jun 12 comment How do I prove $\log(x^n)=n\log|x|$? If you want to prove the above formula for all real $x \neq 0$ and $n \in \mathbb{N}$ (though I'm not sure it'd be true), you need to extend your consideration to complex numbers, extending the domain of $\log$ to complex numbers Jun 12 revised How do I prove $\log(x^n)=n\log|x|$? added 144 characters in body Jun 12 comment How do I prove $\log(x^n)=n\log|x|$? If you consider in real numbers only, the domain of $\log$ should be restricted to $(0,\infty)$. Jun 12 comment How do I prove $\log(x^n)=n\log|x|$? The above formula does not hold for arbitrary real $x$ and natural $n$; in this case $\log$ is not even defined properly