On Sat, 26 Jun 2010 16:01:17 +0200
Tobias Katz <tobi...@web.de> wrote:

> Hi,
> 
> I got a first result, but it only works when I "type" it in the
> command line interface.
> 
> import numpy as np
> import pylab as pl
> 
> pl.ion()
> pl.grid(True)
> 
> var('t n_ ll ul')
> 
> tt=np.arange(0.01,10,0.01)
> 
> f=sin(t)/t
> ts=0.5
> fs=sum(f*dirac_delta(t-(2*n_-1)*ts),n_,0,20)/dirac_delta(0)
> 
> fl=lambda t:f
> fl=fl(t)
> 
> fsl=lambda t:fs
> fsl=fsl(t)
> 
> fslm=map(fsl,tt)
> fsld=np.array(fslm)
> fsld=map(n,fsld)
> 
> pl.vlines(tt,[0],fsld)
> 
> flm=map(fl,tt)
> fld=np.array(flm)
> fld=map(n,fld)
> 
> pl.plot(tt,fld,'--',linewidth=.5)
> 
> 
> 
> When I run it like
> run -i file.py
> I get an error:
> 
<snip>
> AttributeError: 'int' object has no attribute '_maxima_'
> 
> 
> How can I cast these integers to numbers or what is my mistake?
> Is there a better way to do this?

This looks like a bug in the way symbolic sums are handled:

http://trac.sagemath.org/sage_trac/ticket/9393

For a workaround, try renaming your file to have the extension .sage
instead of .py. 


BTW, to any developer reading this: 

A brief search through the tutorial or the FAQ included in Sage didn't
reveal anything to link to, is there a canonical point to refer to for
these questions? Where is the preparser and differences between Python
and Sage documented?


Cheers,
Burcin

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