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Re: beginner's question -- syntax related?


John M. Dlugosz wrote:
> 
> This works:  Plot[{3-Sqrt[5-4x-x^2],3+Sqrt[5-4x-x^2]}, {x, -5, 0}]
> 
> This doesn't:
>         ls := {3-Sqrt[5-4x-x^2],3+Sqrt[5-4x-x^2]}, {x, -5, 0}
> 
>         Plot[ls, {x,-5,0}]
> 
> Somehow, the ls isn't getting taken as the list of two expressions.  I
> tried both = and := when creating ls, with the identical effect.
> 
> Clearly, I'm missing something about syntax.  Can someone help me?
> 
> --John

This may help:

Plot[Evaluate[ls], {x, -5, 0}]

Plot is one of a few, but important functions that do not follow the
standard evaluation procedure. See 2.5.5 of the Mathematica book for an
explanation.


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