On Sun, Apr 6, 2008 at 1:35 AM, Eugene <[EMAIL PROTECTED]> wrote:
>
>  Hi all!
>
>  Help please, I can not understand what is wrong with this:
>
>  f(x)=x;
>  def g(x):
>     if (x>=0):
>         return f(x)
>     else:
>         return f(-x);
>
>  show(plot(g(x),(x,-1,1))) #form1
>  show(plot(g,-1,1)) #form2
>
>  same thing:
>  https://www.sagenb.org/home/pub/1770/
>
>  the two graphics must be same, because it is the same functions.
>  so, why form 2 gives wrong result?

In form 1 g(x) evaluates the function g *exactly* once. It
decides the x>=0 is false (since it isn't *always* true), so
it returns f(-x) since and for all.  That is, g(x) evaluates
to something completely different than g.

Does that make sense?

>
>  P.S. I do not want to plot abs(x) function, that is only for example.
>
>  >
>



-- 
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org

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