Help to build a function to approximate a expression whenX >> Y
Subject: Help to build a function to approximate a expression whenX >> Y
From: Andrey Siver
Date: Tue, 2 Oct 2007 18:33:16 +0400
Dear Javier,
I would recomend You to introduce a new variable, say, t=Y/X and then come
from variables (X,Y) to new variables, say, (t,X). Now You can build series
on the variable t around 0 very easily: F(t) ~ F(0) + F'(0)*t + ...
Another advantage of this method: t is non-dimensional (unitless) variable
(so it will be much more easily to carry out numerical calculations).
Best regards,
-Andrey
----- Original Message -----
From: "Javier Sanchez" <javier_home at terra.es>
To: <maxima at math.utexas.edu>
Sent: Tuesday, October 02, 2007 5:18 PM
Subject: Help to build a function to approximate a expression whenX
>> Y
> Greetings,
>
> I can not solve this very simple problem.
>
> I do have expressions of the form
>
> (a + b + c + d)*x + (d + e )*y +f
>
> I 'd like to approximate these expressions assuming x >> y in the form
>
> (a + b + c)*x + (d + e )*y +f
>
> but I can not build a function that does this approximation
> automatically (with the expression to be approximated and the two
> variables x and y with x >> y as input arguments)
>
> Could you please help me?
>
> Thanks
>
> Javi
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