2021-05-18 02:08:11 +0200 received badge ● Nice Question (source) 2020-08-15 21:51:01 +0200 commented answer Beginner question: How to get y value given x in an equation? Thanks a million. Only think I don't understand is how to use sympy: "sympy is able to find a solution". How do I install sympy? I am on Sage 8.1 running Ubuntu (actually ElementaryOS) See I'm getting this: solve(g.subs(x==1/5),y, algorithm="sympy") [sqrt(y^2 - 4*y + 101/25) == -3/4*sqrt(y^2 + 1/25) + 7/4]  2020-08-15 21:45:05 +0200 commented answer Beginner question: How to get y value given x in an equation? Thank you thank you thank you. You not only solved it, but taught us the way to solve similar problems. Tremendously grateful... I'll work each step out today. 2020-08-15 21:45:05 +0200 received badge ● Commentator 2020-08-15 00:43:55 +0200 asked a question Beginner question: How to get y value given x in an equation? Hi, I have an equation like so (I put in some simplifying values for the constants): var('h1 h2 x y n') n = 4/3 h1 = 1 h2 = 1 g = sqrt(x^2 + y^2) + n * sqrt(x^2 + (h1 + h2 - y)^2) - (h1 + n * h2) == 0  I am able to get a beautiful implicit plot: graph = implicit_plot(g, (x, -0.5, 0.5), (y, 0, 2.5)) show(graph)  But how do I find out the numerical values at say x = 0.2? This doesn't give numerical values (and I don't really understand its result either): solve(g(x=0.2), y)  It gives [sqrt(y^2 - 4*y + 101/25) == -3/4*sqrt(y^2 + 1/25) + 7/4]  Thanks 2020-02-13 18:07:59 +0200 commented answer gen_lengendre_p bug Like. Thanks. 2020-02-13 18:07:11 +0200 received badge ● Supporter (source) 2020-02-13 02:38:42 +0200 answered a question gen_lengendre_p bug Thanks, Eric_G. I am interested to help out. Is there a page with Sage volunteering process? I will sign up. I have computer science degrees but new to math (but seriously interested to learn). Correct definition: def legendre_function(l, m, f): return ((-1)^m * (1 - x^2)^(m/2) * diff(legendre_P(l, x), x, m)).subs(x = f) sage: legendre_function(2, 2, x) -3*x^2 + 3 sage: legendre_function(2, 2, cos(x)) -3*cos(x)^2 + 3  2020-02-12 18:40:28 +0200 asked a question gen_lengendre_p bug Hi, wonder if someone here familiar with associated Legendre function can verify: sage: gen_legendre_P(2, 2, x) 3*x^2 - 3  I think it should be 3 - 3*x^2  In Sage 8.9 Thanks 2020-01-09 21:39:08 +0200 commented answer How to print trailing spaces? Thanks. Extremely useful for fine grain control. 2020-01-09 06:02:24 +0200 commented answer How to print trailing spaces? Very interesting. Thanks. 2020-01-09 02:49:08 +0200 commented question Running Sage in Bash Actually .py suffix should work too. I just notice this: [bryanso@localhost ~]$sage -help SageMath version 8.8, Release Date: 2019-06-26 Optional arguments: file.[sage|py|spyx] -- run given .sage, .py or .spyx file ...  2020-01-09 02:45:35 +0200 commented question Running Sage in Bash If you have a file with Sage commands, make sure you name the file with .sage suffix. At least in Linux, I can do this: [bryanso@localhost ~]$ cat test.sage f = sin(x) / x d = diff(f, x) show(d) [bryanso@localhost ~]\$ sage test.sage cos(x)/x - sin(x)/x^2  2020-01-08 19:33:35 +0200 commented answer How to print trailing spaces? Nice. Thanks! 2020-01-08 18:54:20 +0200 received badge ● Nice Question (source) 2020-01-08 18:19:15 +0200 received badge ● Organizer (source) 2020-01-08 18:07:11 +0200 asked a question How to print trailing spaces? Pretty_Print / show seems to delete trailing spaces: reset() var('x t') Psi = function('Psi')(x, t) V = function('V')(x) show('Plug ', Psi, ', ', diff(Psi, t), ', ', diff(Psi, x, x), ' into ', V)  See after "Plug" and after "into" (screenshot taken from CoCalc Jupyter Sage 8.9 Kernel): 2020-01-07 16:13:12 +0200 commented answer Simple Integration Problem Thanks a lot. 2020-01-07 06:56:49 +0200 commented question Simple Integration Problem Hi desjas, all of your test cases return the same way in Sage 8.0 My problem does not happen in 8.0. I actually tried a few versions up to 8.8. All good. It started in 8.9. So logically I tend to think your test cases may not help pinpoint the error I observed. The follow also errors out. This test does not have conjugate. var('x t') f = function('f')(x, t) g = function('g')(x, t) integrate(g * diff(f, x), x)  2020-01-06 20:42:02 +0200 commented question Simple Integration Problem That clearly looks like a bug. But I am not sure if it is directly related to my problem, which has the same variable x for diff and integrate. But thanks for pointing out this new situation. 2020-01-06 15:07:47 +0200 received badge ● Good Question (source) 2020-01-06 11:33:50 +0200 received badge ● Nice Question (source) 2020-01-06 01:01:26 +0200 asked a question Simple Integration Problem Hi, these simple steps used to work in Sage 8.0. They now give an error in 8.9. I tried in CoCalc, same problem. Do I need to change anything? If this is a Sage regression, how can I work around it? Thanks. Sage 8.0 behavior: sage: var('x t') (x, t) sage: psi = function('psi')(x, t) sage: integrate(conjugate(psi) * diff(psi, x), x) integrate(conjugate(psi(x, t))*diff(psi(x, t), x), x)  In 8.9 it gives: ┌────────────────────────────────────────────────────────────────────┐ │ SageMath version 8.9, Release Date: 2019-09-29 │ │ Using Python 2.7.15. Type "help()" for help. │ └────────────────────────────────────────────────────────────────────┘ sage: var('x t') (x, t) sage: psi = function('psi')(x, t) sage: integrate(conjugate(psi) * diff(psi, x), x) --------------------------------------------------------------------------- ... ValueError: No differentiation variable specified.  Posting the complete trace below: sage: var('x t') (x, t) sage: psi = function('psi')(x, t) sage: integrate(conjugate(psi) * diff(psi, x), x) --------------------------------------------------------------------------- ValueError Traceback (most recent call last) in () ----> 1 integrate(conjugate(psi) * diff(psi, x), x) /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/misc/functional.pyc in integral (x, *args, **kwds) 751 """ 752 if hasattr(x, 'integral'): --> 753 return x.integral(*args, **kwds) 754 else: 755 from sage.symbolic.ring import SR /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx in sage .symbolic.expression.Expression.integral (build/cythonized/sage/symbolic/expression.cpp:64036 )() 12360 R = ring.SR 12361 return R(integral(f, v, a, b, **kwds)) > 12362 return integral(self, *args, **kwds) 12363 12364 integrate = integral /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/symbolic/integration/integral.p yc in integrate(expression, v, a, b, algorithm, hold) 912 return integrator(expression, v, a, b) 913 if a is None: --> 914 return indefinite_integral(expression, v, hold=hold) 915 else: 916 return definite_integral(expression, v, a, b, hold=hold) /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/symbolic/function.pyx in sage.s ymbolic.function.BuiltinFunction.__call__ (build/cythonized/sage/symbolic/function.cpp:11847) () 996 res = self._evalf_try_(*args) 997 if res is None: --> 998 res = super(BuiltinFunction, self).__call__( 999 *args, coerce=coerce, hold=hold) 1000 /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/symbolic/function.pyx in sage.s ymbolic.function.Function.__call__ (build/cythonized/sage/symbolic/function.cpp:6927)() 490 (args[0])._gobj, hold) 491 elif self._nargs == 2: --> 492 res = g_function_eval2(self._serial, (args[0])._gobj, 493 (args[1])._gobj, hold) 494 elif self._nargs == 3: /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/symbolic/integration/integral.p yc in _eval_(self, f, x) 92 for integrator in self.integrators: 93 try: ---> 94 A = integrator(f, x) 95 except (NotImplementedError, TypeError): 96 pass /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/symbolic/integration/external.p yc in sympy_integrator(expression, v, a, b) 66 else: 67 result = sympy.integrate(ex, (v, a._sympy_(), b._sympy_())) ---> 68 return result._sage_() 69 70 def mma_free_integrator(expression, v, a=None, b=None): /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/interfaces/sympy.pyc in _sympys age_integral(self) 307 """ 308 from sage.misc.functional import integral --> 309 f, limits = self.function._sage_(), list(self.limits) 310 for limit in limits: 311 if len(limit) == 1: /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/interfaces/sympy.pyc in _sympys age_mul(self) 204 s = 1 205 for x in self.args: --> 206 s *= x._sage_() 207 return s 208 /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/interfaces/sympy.pyc in _sympys age_derivative(self) 333 f = self.args[0]._sage_() 334 args = [[a._sage_() for a in arg] if isinstance(arg,tuple) else arg._sage_() for arg in self.args[2:]] --> 335 return derivative(f, *args) 336 337 def _sympysage_order(self): /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/calculus/functional.pyc in deri vative(f, *args, **kwds) 129 """ 130 try: --> 131 return f.derivative(*args, **kwds) 132 except AttributeError: 133 pass /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx in sage .symbolic.expression.Expression.derivative (build/cythonized/sage/symbolic/expression.cpp:255 45)() 4172 ValueError: No differentiation variable specified. 4173 """ -> 4174 return multi_derivative(self, args) 4175 4176 diff = differentiate = derivative /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/misc/derivative.pyx in sage.mis c.derivative.multi_derivative (build/cythonized/sage/misc/derivative.c:3016)() 217 if not args: 218 # fast version where no arguments supplied --> 219 return F._derivative() 220 221 for arg in derivative_parse(args): /home/bryanso/sage-8.9/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx in sage .symbolic.expression.Expression._derivative (build/cythonized/sage/symbolic/expression.cpp:25 887)() 4234 return self.gradient() 4235 else: -> 4236 raise ValueError("No differentiation variable specified.") 4237 if not isinstance(deg, (int, long, sage.rings.integer.Integer)) \ 4238 or deg < 1: ValueError: No differentiation variable specified.  2019-12-27 06:40:50 +0200 received badge ● Notable Question (source) 2019-12-27 06:40:50 +0200 received badge ● Famous Question (source) 2018-11-25 21:25:39 +0200 received badge ● Popular Question (source) 2017-11-21 20:24:17 +0200 received badge ● Nice Answer (source) 2017-11-13 10:33:31 +0200 received badge ● Self-Learner (source) 2017-11-13 10:33:31 +0200 received badge ● Teacher (source) 2017-11-13 10:33:29 +0200 received badge ● Nice Question (source) 2017-11-13 07:24:07 +0200 answered a question How To Accept Remote Network Connection I found the answer myself... writing it up here in case other Mac users have the same question: Edit the file /Applications/SageMath-8.0.app/Contents/Resources/sage/local/etc/jupyter/jupyter_notebook_config.py so that it has the following line somewhere: c.NotebookApp.ip = '*' Restart Sage App afterwards. 2017-11-09 21:11:46 +0200 received badge ● Student (source) 2017-11-09 21:10:53 +0200 asked a question How To Accept Remote Network Connection Hi, I use Mac OS's native Sage App. I can access Sage's Jupyter notebook from that Mac using localhost:8888. I researched a bit and find out if another computer needs to browse the same Jupyter notebook, one needs to start juypter by passing --ip '*' (otherwise it only accepts localhost traffic and will give a Connection Refused error). But since I am clicking a Mac OS Sage icon to start the server... I am not sure how I can specify the command line option. Please give me some hints. Thanks