# Julien's profile - activity

 2024-01-18 13:44:47 +0200 received badge ● Famous Question (source) 2020-12-27 09:39:17 +0200 received badge ● Notable Question (source) 2019-11-01 10:12:22 +0200 received badge ● Popular Question (source) 2019-11-01 10:12:22 +0200 received badge ● Notable Question (source) 2019-04-10 00:56:34 +0200 asked a question Elliptic Integral Bug? Hi, How did Sage come up with a nice answer when being asked to compute the following elliptic integral of the second kind? $$\int \sqrt{1-(1/2)\sin^2(x)}dx$$ Using integral(f(x),x), SageMathCell returns: $$-\frac{\sqrt{2}}{48}(\sin(3x)-\sin(x))$$ Here is the link. Is it my maths, or is it bug? Thanks, Julien 2018-03-19 16:35:06 +0200 asked a question Error when making it a function This code works for my 3d graph. But when I turn it into a function for an @interact, it does not work anymore. How can I fix this? Thanks. Edit: here is the code: x, y, z = var('x, y, z') @interact def graphe(f = input_box(default=cos(y), label="$f(x,y)$"), r = input_box(default=10, label="$r$")): G = implicit_plot3d(z==f(x,y), (x, -r, r), (y, -r, r), (z, -r, r), plot_points=30, color='orange', mesh=1, opacity=.7) show(G, spin=1)  2017-04-25 01:13:19 +0200 received badge ● Popular Question (source) 2016-11-05 15:24:37 +0200 received badge ● Nice Question (source) 2015-10-22 02:24:56 +0200 received badge ● Supporter (source) 2015-10-22 02:24:13 +0200 commented answer How to use matrices with @interact thanks a lot. 2015-10-21 02:00:58 +0200 commented answer How to use matrices with @interact thanks @kcrisman: if possible, I was hoping for a ready-made command because I have not been able to adapt the documentation I found (including the one you refer to) about input_grid to this context. I really tried before asking. 2015-10-21 01:18:34 +0200 commented answer How to use matrices with @interact It works, thanks. Do you know how to use input_grid in this context? 2015-10-20 22:51:04 +0200 received badge ● Editor (source) 2015-10-20 22:50:23 +0200 asked a question How to use matrices with @interact I found the following example here. @interact def _(m=('matrix', identity_matrix(2))): print m.eigenvalues()  Unlike the other examples I've tried, this one does not work when evaluated in SageMathCell. But it works well in a SageMathCloud Worksheet. What am I supposed to do to produce such a matrix interact that works when I embed it in html pages? 2015-10-17 21:56:45 +0200 received badge ● Scholar (source) 2015-10-17 21:18:32 +0200 received badge ● Student (source) 2015-10-17 17:01:02 +0200 asked a question Is this a known bug with integral() I've tried to compute the following integral wth integral() in a SageMathCloud worksheet: $\displaystyle \int_{-\pi/6}^{\pi/6}\frac{\cos x}{1+\sin x}dx$. The output was an error message (saying the integral is divergent), just like the one I got in SageMathCell (see link): https://sagecell.sagemath.org/?z=eJzz... So I tried with integrate() and with numerical_integral() as well. I was never able to obtain the value of this integral, which turns out to be $\ln(3)$ after an obvious substitution. Is this a bug? Note that replacing 1 by 1.1 yields this: https://sagecell.sagemath.org/?z=eJzz... while we get that when replacing 1 by 2: https://sagecell.sagemath.org/?z=eJzz...