2014-08-22 19:12:06 -0500 received badge ● Scholar (source) 2014-08-21 12:45:25 -0500 commented answer Simplification of atan Thanks. Unfortunately, it seems that the solution is not general enough. For example. arctan(sin(2,hold=True)/cos(2,hold=True)).trigreduce() gives an error AttributeError: 'sage.symbolic.expression.Expression' object has no attribute 'trigreduce' instead of returning 2. 2014-08-21 12:39:11 -0500 commented answer Simplification of atan Thanks. Trying to follow your first suggestion, do you know a way to simplify further iterations? Since f(f(f(f(x))) results in e^(16/5*I*pi) and not, say, e^(6/5*I*pi). 2014-08-21 12:35:26 -0500 received badge ● Editor (source) 2014-08-20 20:13:28 -0500 asked a question Simplification of atan I'm teaching a course on dynamical systems based on the book by Devaney. Today I tried to show the map $f(\theta)=2\theta$ on the circle using Sage, where $\theta$ is given in radians. I could not find functions already defined to perform addition in $\mathbb{R}$ modulo $2\pi$, so I tried to devise my own. I stumbled upon this problem: atan(sin(1/5*pi)/cos(1/5*pi))  produces arctan(4*sin(1/5*pi)/(sqrt(5) + 1)).  Is there a way to obtain 1/5*pi? (By the way, _.simplify() does nothing in this case.) 2011-09-27 07:40:29 -0500 commented answer Is there a way to make an audible noise when a computation is complete? mplayer: relocation error: /usr/lib/libldap_r-2.4.so.2: symbol gnutls_certificate_get_x509_cas, version GNUTLS_1_4 not defined in file libgnutls.so.26 with link time reference 32512 2011-09-27 07:39:58 -0500 commented answer Is there a way to make an audible noise when a computation is complete? Sorry, here with Sage 4.7.1 and Ubuntu 10.04: os.system('mplayer /usr/share/sounds/ubuntu/stereo/phone-incoming-call.ogg') gives