Re: Plotting
- To: mathgroup at smc.vnet.net
- Subject: [mg73009] Re: Plotting
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Sun, 28 Jan 2007 01:44:00 -0500 (EST)
- Organization: The Open University, Milton Keynes, UK
- References: <epfa83$doc$1@smc.vnet.net>
Rayne 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
>
The correct syntax is
f = x^3 - 16*x^2 + 3*x + 1;
Plot[f, {x, -1, 20}];
Also
Plot[x^3 - 16*x^2 + 3*x + 1, {x, -1, 20}];
Regards,
Jean-Marc