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Re: Plotting

• To: mathgroup at smc.vnet.net
• Subject: [mg73024] Re: Plotting
• From: "dimitris" <dimmechan at yahoo.com>
• Date: Mon, 29 Jan 2007 04:51:40 -0500 (EST)
• References: <epfa83$doc$1@smc.vnet.net>

First have a look at the following links:

http://library.wolfram.com/infocenter/Conferences/180/
http://library.wolfram.com/infocenter/Conferences/181/
http://library.wolfram.com/infocenter/Conferences/179/

Then

f[x_] := x^3 - 16*x^2 + 3*x + 1

Plot[f[x], {x, -3, 20}, Axes -> {True, False}, AxesStyle -> 
GrayLevel[0.7], Frame -> {True, True, False, False},
   FrameLabel -> TraditionalForm /@ {x, HoldForm[f[x]]}, FrameTicks -> 
{Range[-5, 20, 5], Range[-600, 800, 400]},
   Epilog -> {Blue, AbsolutePointSize[6], (Point[{#1, 0}] & ) /@ (x /. 
NSolve[f[x] == 0])}, ImageSize -> 400];

On Jan 27, 12:41 pm, "Rayne" <ghcgw... at singnet.com.sg> wrote:
> Hi all,
> I want to plot the cubic equation f(x) == x^3 - 16x^2 + 3x + 1 == 0. I had:
>
> f==x^3-16 x^2+3 x+1 ==== 0
> Plot[f,{x,-1,20}]
>
> but I was unable to get the plot. The error message says
>
> Plot::plnr: f is not a machine-size real number at x == -0.999999.
> Plot::plnr: f is not a machine-size real number at x == -0.148093.
> Plot::plnr: f is not a machine-size real number at x == 0.780985.
> General::stop: Further output of Plot::plnr
>      will be suppressed during this calculation.
>
> How do I get around this problem?
>
> Thank you.
>
> Regards,
> Rayne