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Jan
31
comment Understanding projectile motion formula with air resistance
2D quadratic drag was also considered in this Phys.SE post and links therein.
Jan
29
answered Conjugate elements of $SO(3)$ group
Jan
25
comment HOW to work out mixed partial derivatives
Related question by OP: math.stackexchange.com/q/1625261/11127
Jan
14
comment Problem with differential equation RLC circuit serie
Crossposted to physics.stackexchange.com/q/229322/2451
Dec
29
comment Fourier transform of $ \log(x^{2}+a^{2}) $
Comment to the question (v4): For $u\neq 0$, if one integrates OP's integral $\int_{\mathbb{R}} \! dx \cos(ux) \ln\sqrt{x^2+a^2}$ by parts, and formally ignore the boundary terms (which one rigorously can't), one gets the following integral $\int_{\mathbb{R}} \! dx \frac{\sin(ux)}{u} \frac{x}{x^2+a^2}=-\frac{\pi}{|u|}e^{-|au|}$.
Dec
29
revised Is the exponential map to the indefinite special orthogonal groups $SO^+(p,q)$ surjective?
Added explanation
Dec
28
comment What is differential time ratio?
Crossposted to physics.stackexchange.com/q/226265/2451
Dec
20
revised Prove 'every Positive Definite Matrix is Symmetric BUT not the other way around'
Added explanation cf. comment by OP.
Dec
20
comment Prove 'every Positive Definite Matrix is Symmetric BUT not the other way around'
One needs to use the properties of a sesquilinear form. I updated the answer. Let me know if it is still unclear.
Dec
16
awarded  Custodian
Dec
16
reviewed Approve Is the exponential map to the indefinite special orthogonal groups $SO^+(p,q)$ surjective?
Dec
14
answered Is the exponential map to the indefinite special orthogonal groups $SO^+(p,q)$ surjective?
Dec
14
revised If $XYZ=ZXY$ does $e^Xe^Ye^Z=e^Ze^Xe^Y$?
Forgot some i's.
Dec
14
answered If $XYZ=ZXY$ does $e^Xe^Ye^Z=e^Ze^Xe^Y$?
Dec
14
comment Is time-1 map of a Hamiltonian vector field defined on a cylinder always twist?
Crossposted to physics.stackexchange.com/q/223881/2451
Dec
12
revised Prove 'every Positive Definite Matrix is Symmetric BUT not the other way around'
Added details to counterexample.
Dec
12
answered Prove 'every Positive Definite Matrix is Symmetric BUT not the other way around'
Dec
6
comment Hermitian matrix has positive eigenvalues
Comment to the post (v1): Title question seems different from question in body.
Dec
2
revised conservation law for the trajectories
Added explanation
Dec
1
revised conservation law for the trajectories
Added explanation