Re: Plotting
- To: mathgroup at smc.vnet.net
- Subject: [mg73000] Re: Plotting
- From: Peter Pein <petsie at dordos.net>
- Date: Sun, 28 Jan 2007 01:07:54 -0500 (EST)
- References: <epfa83$doc$1@smc.vnet.net>
Rayne schrieb: > 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 > Hi Rayne, read about basic syntax issues in the help browser. Didn't you realize the syntax error "f==x^3...===0 can not be followed by =0"? My crystall ball fails terribly. if you want f to be the root(s) of a polynomial, the value(s) will be constants. And if you want to plot the values of a polynomial, what does the "====0" mean. What do 4 "="s mean at all and why do you ask Mathematica if f is equal to x^3-16x^2+3x+1====0? Where has f been defined? Why don't you care about syntax errors? I really do not understand what you want, sorry. Peter -- http://moratoriumcampaign.org/