[sage-support] list of functions

[martin Campos Pinto]

Hi again,
... and again sorry if this is a newbie's question:

so when I type (in my sage Notebook 3.2.3)

a = [i for i in range(2)]
a[0]

I get 0 (which is fine), now when I type

b = [lambda x:i for i in range(2)]
b[0](0)

I get 1 ... There must be a simple explanation for this but I can't
figure it out. What's wrong ?

Thanks in advance, (sage is really wonderful :-)
- Martin

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[sage-support] Strange behaviour of float()?

[martin Campos Pinto]

Hi everybody,

in my Notebook (version 3.2.3) I get the following:

sage: a = float(11)
sage: a

0.0

sage: var('x')
sage: b(x) = float(x1)

Traceback (most recent call last):
  File stdin, line 1, in module
  File /Users/campos/.sage/sage_notebook/worksheets/admin/4/code/
204.py, line 8, in module
_=var(x);b=symbolic_expression(float(x_sage_const_1 )).function
(x)
  File /Applications/sage/local/lib/python2.5/site-packages/
SQLAlchemy-0.4.6-py2.5.egg/, line 1, in module

TypeError: float() argument must be a string or a number

... is this a normal behaviour for float()? And sorry is this is a
silly question!
-- Martin

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[sage-support] Re: list of functions

[martin Campos Pinto]

 This is caused by the scoping rules for Python's lambdas and list
 comprehensions.  See the question and answer here for an 
 explanation:http://stackoverflow.com/questions/139819/why-results-of-map-and-list...

 --Mike

...ok, so, a way to write it would be
b = [lambda x,u=i:u for i in range(2)]

Thanks for the link, that was very helpful.
-- Martin
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