On Sat, Aug 15, 2009 at 11:02 AM, Mani chandra<mchan...@iitk.ac.in> wrote: > > William Stein wrote: >> On Sat, Aug 15, 2009 at 5:44 AM, Mani chandra<mchan...@iitk.ac.in> wrote: >> >>> Hi, >>> >>> I wrote a code in sage to construct a Low Dimensional model for the >>> Magnetohydrodynamic equations to study dynamos etc... But the program >>> crashes at different points on different machines with the following error: >>> >>> Traceback (most recent call last): >>> File "./LowD_model.py", line 158, in <module> >>> du_x_dt.append(select_mode(RHS_Ux, l, m, n) ) >>> File "./LowD_model.py", line 28, in select_mode >>> val = (func*exp(-I*(l*x + m*y + >>> n*z))).integrate(x,0,2*pi).integrate(y,0,2*pi).integrate(z,0,2*pi) >>> File "expression.pyx", line 5700, in >>> sage.symbolic.expression.Expression.integral >>> (sage/symbolic/expression.cpp:24436) >>> File >>> "/opt/sage/sage/local/lib/python2.6/site-packages/sage/calculus/calculus.py", >>> line 566, in integral >>> result = expression._maxima_().integrate(v, a, b) >>> File >>> "/opt/sage/sage/local/lib/python2.6/site-packages/sage/interfaces/maxima.py", >>> line 2003, in integral >>> return I(var, min, max) >>> File >>> "/opt/sage/sage/local/lib/python2.6/site-packages/sage/interfaces/expect.py", >>> line 1382, in __call__ >>> return self._obj.parent().function_call(self._name, [self._obj] + >>> list(args), kwds) >>> File >>> "/opt/sage/sage/local/lib/python2.6/site-packages/sage/interfaces/expect.py", >>> line 1290, in function_call >>> return self.new(s) >>> File >>> "/opt/sage/sage/local/lib/python2.6/site-packages/sage/interfaces/expect.py", >>> line 1086, in new >>> return self(code) >>> File >>> "/opt/sage/sage/local/lib/python2.6/site-packages/sage/interfaces/expect.py", >>> line 1021, in __call__ >>> return cls(self, x, name=name) >>> File >>> "/opt/sage/sage/local/lib/python2.6/site-packages/sage/interfaces/expect.py", >>> line 1425, in __init__ >>> raise TypeError, x >>> TypeError: Error executing code in Maxima >>> CODE: >>> sage2436 : integrate(sage2432,sage2433,sage2434,sage2435)$ >>> Maxima ERROR: >>> >>> Maxima encountered a Lisp error: >>> >>> Memory limit reached. Please jump to an outer point or quit program. >>> >>> Automatically continuing. >>> To reenable the Lisp debugger set *debugger-hook* to nil. >>> >>> >>> I'm attaching the entire code but the function where it crashed is the >>> follows: >>> >>> def select_mode(func,l,m,n): >>> val = (func*exp(-I*(l*x + m*y + >>> n*z))).integrate(x,0,2*pi).integrate(y,0,2*pi).integrate(z,0,2*pi) >>> return val/(8*pi**3) >>> >>> Also, I'd like to know if the symbolic computation backend for SAGE is >>> Maxima, Pynac or Sympy? Or is it a combination of all the three? >>> >> >> All three, though I don't think anything from sympy is used by default. >> >> >>> Will >>> SAGE move to a single backend in the future? >>> >> >> It will be much better if Sage moves away from Maxima, as your >> question nicely illustrates. Here's a big shout of encouragement to >> everybody out there who is working on code to make it so Sage doesn't >> depend at all on Maxima for symbolic calculus. >> >> >>> If this bug can't be fixed, >>> is it suggested that I rewrite the code using the Sympy library? >>> >>> >> >> Is it really a bug? It says "Memory limit reached." Running out of >> memory isn't necessarily a bug. Computers have finite RAM. >> >> What operating system, computer hardware, etc. are you using? Without >> that info it is very hard to be more helpful. >> >> >>> P.S If anyone is running the code, then please note that it takes a LOT >>> of time. >>> >>> Thanking you, >>> Mani chandra >>> >>> >> >> >> >> > Hi, > I forgot to add hardware info. The program is using nowhere close to > the 4 GB limit on my computer. I'm using Archlinux x86_64, kernel > 2.6.30. I also tried it on another machine which has 1 GB of ram (which > also is not being used fully) and which has Archlinux x86_64, kernel > 2.6.28 . > > I totally agree that symbolic calculus backend be changed from Maxima to > whatever is the best out there. I've had so many (other)troubles with > Maxima in SAGE, with "assume", "solve", etc... As it stands, It simply > is not an elegant system.
+1 If you want to launch into a project to just rewrite (say) solve natively in Sage, that would be great. Somebody will have to do it. And the sooner the better. You might experiment with: sage: f = x^2 sage: f.integrate(algorithm='sympy') 1/3*x^3 William --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
