hi Florian
Florian Beutler wrote:
> hallo
> I just installed sage today and probably the problem I have at the
> moment is a typical beginner problem, but unfortunately the tutorial
> was not helpful concerning this points.
>
I was in the same situation 3 weeks ago. I have the same feeling with
the manual, and as soon as I get a little bit more familiar with Sage
and the programming/documentation I will try to make some contributions
to the manual. I would recommend you 2 things.
1.- Take a look to "Sage For Newbies". Google it, its for free and it
takes approximately 20 min to read the guide and become familiar with
the easy things of Sage.
2.- Log in into the Sage database (sagenb.org) and have a look to the
literally thousands of worksheets there. Many people (included myself)
leave its guides and ways to solve certain task with Sage.
> if I use
> rho = 0.0058/((r/2.4)*(1+(r/2.4))^2)
> integral(rho,r,0,100000)
>
> this does not work because for r=0 rho is not defined. But anyway I
> want to integrate over the complete radius. What do I have to do?
> I can avoid the problem by using
>
Use the following to define r as symbolic variable
r=var('r')
rho = 0.0058/((r/2.4)*(1+(r/2.4))^2
and solve the integral numerically with the n() method (see The Sage
Tutorial page 6)
sage: integral(rho,r,1E-5,1E5).n()
0.158526563291981
> integral(rho,r,0.000001,100000)
> this gives:
> 0.01392*(10.6953303525 - (125003*log(500012) - 125003*log(100000) - 3)/
> 125003)
> how is it possible to force sage to give me one value and not this
> helpless term above?
> thanks
> regards
> florian
>
> >
>
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