Re: beginner's question -- syntax related?
- To: mathgroup at smc.vnet.net
- Subject: [mg13369] Re: [mg13284] beginner's question -- syntax related?
- From: BobHanlon at aol.com
- Date: Mon, 20 Jul 1998 02:50:22 -0400
- Sender: owner-wri-mathgroup at wolfram.com
John,
Plot[{3-Sqrt[5-4x-x^2],3+Sqrt[5-4x-x^2]}, {x, -5, 0}];
ls[x_] := {3-Sqrt[5-4x-x^2],3+Sqrt[5-4x-x^2]};
??Plot
"Plot[f, {x, xmin, xmax}] generates a plot of f as a function of x from
xmin \ to xmax. Plot[{f1, f2, ... }, {x, xmin, xmax}] plots several
functions fi." Attributes[Plot] = {HoldAll, Protected}
Options[Plot] = {AspectRatio -> GoldenRatio^(-1), Axes -> Automatic,
AxesLabel -> None, AxesOrigin -> Automatic, AxesStyle -> Automatic,
Background -> Automatic, ColorOutput -> Automatic, Compiled -> True,
DefaultColor -> Automatic, Epilog -> {}, Frame -> False,
FrameLabel -> None, FrameStyle -> Automatic, FrameTicks ->
Automatic,
GridLines -> None, ImageSize -> Automatic, MaxBend -> 10.,
PlotDivision -> 30., PlotLabel -> None, PlotPoints -> 25,
PlotRange -> Automatic, PlotRegion -> Automatic, PlotStyle ->
Automatic,
Prolog -> {}, RotateLabel -> True, Ticks -> Automatic,
DefaultFont :> $DefaultFont, DisplayFunction :> $DisplayFunction,
FormatType :> $FormatType, TextStyle :> $TextStyle}
Note that Plot has Attribute HoldAll. You need to Evaluate the list for
Plot to work in the second form.
Plot[Evaluate[ls[x]], {x,-5,0}];
Bob Hanlon
In a message dated 7/17/98 8:53:51 AM, john at dlugosz.com 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?