tdstephens3's profile - activity

I am not sure whether your overall goal is worth pursuing. From the surface, it looks like MyFunc is becoming a clone of sage.symbolic.expression.Expression. Additionally, Sage has a deprecation policy: old code must be supported for at least twelve months with deprecation warnings before Sage can break it. For most purposes, I suggest keeping Sage up to date and continually testing whether your code is using a deprecated interface.

Just for reference, your example can be done in Sage as follows:

Using a symbolic function:

sage: func(x) = function('func', x)
sage: func
x |--> func(x)
sage: func(3)
func(3)
sage: func.differentiate(x)
x |--> D[0](func)(x)
sage: func.differentiate(x)(3)
D[0](func)(3)

Using a concrete function:

sage: func(x) = sinh(x) * sqrt(x)
sage: func
x |--> sqrt(x)*sinh(x)
sage: func(3)
sqrt(3)*sinh(3)
sage: RR(func(3))
17.3514683581443
sage: func.differentiate(x)
x |--> sqrt(x)*cosh(x) + 1/2*sinh(x)/sqrt(x)
sage: RR(func.differentiate(x)(3))
20.3296134831414

As far as I know, the above functionality has been around for a while without any changes, so I would not be too concerned about the stability of Sage's interface.

Sage is looking for those bindings installed in Sage's copy of python. You can install things in Sage's copy of python by doing "sage -sh" and then whatever you normally would do to install the python bindings.

For Sage's matplotlib, the graphical guis are also turned off by default. Define the environment variable:

export SAGE_MATPLOTLIB_GUI=yes

and then reinstall Sage's matplotlib:

sage -i matplotlib

to compile support for other backends in Sage.

For Sage's matplotlib, the graphical guis are also turned off by default. Define the environment variable:

export SAGE_MATPLOTLIB_GUI=yes

and then reinstall Sage's matplotlib:

sage -i matplotlib

to compile support for other backends in Sage.

I am trying to solve the problem I was having in this question - but since I did a clean sage install since then I figured I would start a new question.

I am writing python modules and running them with sage-python (currently, python-2.6.4.p10). I need some plotting capability, both to the screen and plots written to files. My plan is to use matplotlib.pyplot for this (but I will gladly abandon pyplot if it is appropriate).

The problem is this:

From the bash prompt with matplotlibrc backend specified as GTKAgg:

bash$ sage-python
>>>import matplotlib.pyplot
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/opt/sage/local/lib/python2.6/site-packages/matplotlib/pyplot.py", line 95,    
in <module>
new_figure_manager, draw_if_interactive, show = pylab_setup()
File "/opt/sage/local/lib/python2.6/site-
packages/matplotlib/backends/__init__.py", line 25, in pylab_setup
globals(),locals(),[backend_name])
File "/opt/sage/local/lib/python2.6/site-
packages/matplotlib/backends/backend_gtkagg.py", line 10, in <module>
from matplotlib.backends.backend_gtk import gtk, FigureManagerGTK, 
FigureCanvasGTK,\
File "/opt/sage/local/lib/python2.6/site-
packages/matplotlib/backends/backend_gtk.py", line 11, in <module>
raise ImportError("Gtk* backend requires pygtk to be installed.")
ImportError: Gtk* backend requires pygtk to be installed.

From the bash prompt with matplotlibrc backend specified as TkAgg:

bash$ sage-python
>>>import matplotlib.pyplot
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/opt/sage/local/lib/python2.6/site-packages/matplotlib/pyplot.py", line 95, 
in <module>
new_figure_manager, draw_if_interactive, show = pylab_setup()
File "/opt/sage/local/lib/python2.6/site-
packages/matplotlib/backends/__init__.py", line 25, in pylab_setup
globals(),locals(),[backend_name])
File "/opt/sage/local/lib/python2.6/site-
packages/matplotlib/backends/backend_tkagg.py", line 11, in <module>
import matplotlib.backends.tkagg as tkagg
File "/opt/sage/local/lib/python2.6/site-packages/matplotlib/backends/tkagg.py", 
line 1, in <module>
import _tkagg
ImportError: No module named _tkagg

Now, I am running Arch Linux and according to my package manager, pacman, I have

extra/pygtk 2.24.0-1 [installed]
Python bindings for the GTK widget set

extra/tcl 8.5.10-1 [installed]
The Tcl scripting language

extra/tk 8.5.10-1 [installed]
A windowing toolkit for use with tcl

I have looked here but I don't see how to get tk8.5-dev since I don't use the Debian repositories (it seems to be available for Ubuntu and Debian).

It may be that I simply have an environment variable defined incorrectly, maybe I need to choose another backend for matplotlib, or need to abandon the pyplot module, what do you think?

Emerson, these are directives specified in the .bashrc or .bash_profile file sitting in your home directory. The best thing for you to do is to learn about the .bashrc file (and the .bash_profile file) in general, then look into what are known as environment variables, which are these PATH things they are talking about.

What about the efficiency of each/any of the above methods? In particular, is unpacking the dictionary quicker than unpacking the list?

I agree that MyFunc is a clone of sage.symbolic.expression.Expression, but I *think* that is what I want here. I am trying to have these symbolic expressions available to a larger system written in python... I am rewriting a large amount of OO Matlab code in python. For better or worse, I am being guided by my earlier design patterns. Is there a deprecation issue with the code I have written?

Alright, I guess it works this way sometimes (ask question, five minutes later figure out the answer!)

Using the information here (Sage tutorial), we can build a CallableSymbolicExpression. Here's what I did for this specific example:

import sage.all as sage

class myFunc:

   def __init__(self):
      sage.var('x')
      expr = x+1
      self.expr = expr.function(x)

   def __call__(self,value):
      return self.expr(value)

   def diff(self):
      return self.expr.diff(x)

This uses the Sage function(...) method as explained in the link. It is clean and I like it.

I am trying to obtain a callable symbolic expression from a python script and having a hard time of it.

In my python script I would like to have something along the lines of:

func = myFunc()
func_evaluated_at_3 = myFunc(3)

func_dx = func.differentiate()
func_dx_evaluated_at_3 = func_dx(3)

In the module defining myFunc I was hoping to have something along the lines of:

import sage.all as sage

class myFunc:

   def __init__(self):

      sage.var('x')
      self.expression = x + 1
      # maybe this should be: self.expression = sage.preparse("f(x) = x + 1")?

   def __call__(self,value):
       return self.expression(value)

   def differentiate(self):
      return self.expression.diff(x)

The goal is to keep the client code that constructs, calls, and manipulates objects of type myFunc from knowing about Sage. Perhaps I am misguided, any help would be appreciated. (also, help with the appropriate tags would be, well, helpful)