bbtp's profile - activity

Emmanuel, you're right about the examples being in the tutorial. Thanks for taking the time to run the equations. Since they worked out for you, the problem is not in the code or Sage. In fact, I no longer get the error about calling tuples. Apparently, there was a conflict with other software on my computer. When I just used the python interpreter, I had to unset PYTHONHOME in order to start the interpreter. Looks like Sage is not the problem here.

Thanks for the info. This definitely helps me understand what the error message normally means. However, in this case I don't know if the error message really relates to the input; for example:
sage: x, b, c = var('x b c') sage: solve([x^2 + b*x + c == 0],x) gave the error message in notebook(), but in terminal the standard solution for the quadratic formula with no error .

eric__g's comment that the code ran fine for him in both terminal and notebook() suggested that the problem was in my system as opposed to being a bug in Sage.

I was going to unset PYTHONHOME, but first I ran the code again in notebook() and it ran without error. I am going to mark this question as solved as it is no longer reproducible.

I would give credit to eric__g, but don't see any way to do mark a comment as an answer.

It seems unlikely that running the code in terminal would change anything on my computer that would allow the code to subsequently run in notebook() without error. All I can say is that the code (one example is in my original post) now runs without error, while originally it did not.

Not much of an answer, but the best I can do, Bob.

Just downloaded sage-8.0-Debian_GNU_Linux_8-x86_64.tar.bz2. Seems to be working well. Great work as always!

Trying to solve simultaneous equations. Get error "TypeError: 'tuple' object is not callable."

Found exactly the examples I needed in Basic Algebra and Calculus. Solving Equations (online Sage reference). Copied and pasted Jason Grout's example and also the examples above it. Get error message "TypeError: 'tuple' object is not callable." in notebook() , but examples work in terminal.

Here is one of the examples that gives the error in notebook() (but works in terminal). sage: x, b, c = var('x b c') sage: solve([x^2 + b*x + c == 0],x)

What am I missing here?

Any ideas? Thanks.

Installing 5.3 helped a lot. Still have some issues, but making progress. Should I uninstall 4.7.1, it is in a different directory; will it cause interference?

Thanks, Bob

update: after running 'sage -f python' , python 2.7.3.p0 was downloaded and installed (python 2.6.4.p11 standard in 4.7.1). Now, unable to start sage; get message 'No module named IPython. Any suggestions?

I am trying to follow instructions at http://sagemath.org/doc/numerical_sag..., "Installing Visualization Tools on Linux". (sage 4.7.1 on Ubuntu 12.04).

These instructions recommend getting Tkinter to work. I have been unable to do so for similar reasons as June 7 post, "Tkinter for sage 5.0 on linux."

In response to that post, V. Braun suggests not using Tkinter.
Should I ignore initial instructions under "Installing Visualization..." relating to Tkinter?

Thanks, Bob

Am trying to follow instructions at http://sagemath.org/doc/numerical_sage/installation_linux.html, Installing Visualization Tools on Linux (sage 4.7.1 on Ubuntu 12.04). These instructions recommend getting Tkinter to work. Have been unable to do so for similar reasons as post above. V. Braun suggests not using Tkinter, Should I ignore instructions under "Installing Visualization..." relating to Tkinter? Thanks, Bob

Thanks Calc314 for the post up above answering my questions about plotting negative and the link to Rice.edu. I've used pplane with mathlab, but I no longer have mathlab so good to know pplane can be used independently. Bob

Thanks calc314 for the link to Wolfram Alpha. Quite a goldmine, there. Especially liked the 3d (2d real, 1d imaginary) plot of erf. Maybe someday I'll learn how to make a similar plot for the solution of y'+2xy =1.

Your code for the numerical approximation and the slope fields is very interesting. I assume you used 1-xy as a simplification: it doesn't change the shape of the curve in the maxima code plots much. But when I plug in 1-2xy into your code, I have trouble with the y axis coordinates. If I plug 1-2x*y into your code, what is the best way to set the actual plot y coordinates back to say -0.8 to 0.8 and the x coordinates from -10 to 20? Thanks again, Bob

Thanks for all the helpful comments. I now vaguely remember having been unable to plot the error function in Sage before.

Plotting as a vector field works:

maxima.eval('load("plotdf")')

maxima.eval('plotdf(-2xy+1,[trajectory_at,0,0],[x,-3,3],[y,-3,3])')

f = desolve(diff(y,x) + 2xy - 1, y, ics=[0,0]); f plot(f) # error message ... unable to simplify to float approximation.

Tried plotting real_part of solution: -1/2Isqrt(pi)e^(-x^2)erf(I*x), but get same error message.

Tried using list_plot, but error about symbolic expression. Haven't been able to get implicit_plot or sol.simplify_full to work.

Thanks for any hints.