Re: Coloring curves: not as simple as it sounds..
- To: mathgroup at smc.vnet.net
- Subject: [mg118157] Re: Coloring curves: not as simple as it sounds..
- From: Chris Rodgers <see-rodgers-org-uk-for-contact-details at invalid.gg>
- Date: Thu, 14 Apr 2011 07:08:43 -0400 (EDT)
- References: <io6d17$dpl$1@smc.vnet.net>
Not a full explanation, but try this:
Plot[Evaluate[{a x, a x^2, a x^3} /. {a -> 1}], {x, 0, 2},
PlotStyle -> {Red, Green, Blue}]
That works for me.
Now run
Attributes[Plot]
So, the issue is to do with the HoldAll attribute on Plot. I guess when
Plot counts the number of lines it is expecting to produce, it doesn't
untangle your rule replacement.
C.
On 14/04/2011 09:59, Jean-Michel Di Nicola wrote:
> All,
>
> I have a question that looks fairly trivial, but I cannot solve it....
> Please help!
>
> Thanks, JM
>
> Here is a simplified toy example.
> When I type
> Plot[{a x /. {a -> 1}, a x^2 /. {a -> 1}, a x^3 /. {a -> 1}}, {x, 0,
> 2}, PlotStyle -> {Red, Green, Blue}]
> I get 3 curves with different colors.
>
> Well, when I type
> Plot[{a x, a x^2, a x^3} /. {a -> 1}, {x, 0, 2},
> PlotStyle -> {Red, Green, Blue}]
> I get 3 curves but they are all blue, WHY?
>
> However, when I evaluate {a x /. {a -> 1}, a x^2 /. {a -> 1}, a x^3 /.
> {a -> 1} and {a x, a x^2, a x^3} /. {a -> 1}, they both give the same
> result....{x, x^2, x^3}.
>
> Thank you for your help!!!
>