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