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Jan
29
comment Why is integration so much harder than differentiation?
Differentiation is more difficult.
Jan
11
comment Obtaining an estimate for the Lagrangian $L=H^*$ from the Hamiltonian $H$
Wonderful, thanks.
Jan
11
accepted Obtaining an estimate for the Lagrangian $L=H^*$ from the Hamiltonian $H$
Jan
11
comment Obtaining an estimate for the Lagrangian $L=H^*$ from the Hamiltonian $H$
@epimorphic using $v_1$ and $v_2$ such that $L(v_j)=p_j\cdot v_j - H(p_j), j=1,2.$
Jan
8
awarded  Nice Question
Jan
4
comment Obtaining an estimate for the Lagrangian $L=H^*$ from the Hamiltonian $H$
@user226970 I see how that works out now, thanks. I saw a hint in some notes that points to another way of doing it so I'll hold out to see if anyone comes up with an alternative.
Jan
3
comment An exemple of measurable function $f$ on $\mathbb R^2$ s.t. $f^y$ is not mesurable for every $y$.
Ok. Then your example works. Be careful with your English. Change "every" to "some".
Jan
3
comment An exemple of measurable function $f$ on $\mathbb R^2$ s.t. $f^y$ is not mesurable for every $y$.
@user301068 You want $f^y$ to be nonmeasurable for every $y,$ right?
Jan
3
comment An exemple of measurable function $f$ on $\mathbb R^2$ s.t. $f^y$ is not mesurable for every $y$.
When $y=1$, $f^y\equiv 0,$ which is measurable.
Jan
3
comment Global Lyapunov function. Definition
You get $+\infty$ in some directions and $-\infty$ in others. Namely, when $y=0$ you get $\infty$ as $x\to -\infty,$ $-\infty$ as $x\to \infty$. So, there is no limit.
Jan
3
comment Global Lyapunov function. Definition
@Rhjg Yes, I've edited it.
Jan
3
revised Global Lyapunov function. Definition
added 10 characters in body
Jan
3
answered Global Lyapunov function. Definition
Jan
1
comment Obtaining an estimate for the Lagrangian $L=H^*$ from the Hamiltonian $H$
@mvw newer editions have $v_1, v_2$ instead of $q_1, q_2.$
Jan
1
asked Obtaining an estimate for the Lagrangian $L=H^*$ from the Hamiltonian $H$
Dec
8
awarded  Notable Question
Oct
26
awarded  Nice Question
Sep
30
awarded  Notable Question
Aug
18
awarded  Yearling
Apr
17
accepted Smooth maps (between manifolds) are continuous (comment in Barrett O'Neill's textbook)