[vox] Graphy on octave or Maxima

[Jeff Newmiller]

On Wed, 14 Jul 2004, Ken Bloom wrote:

> On Wed, Jul 14, 2004 at 10:36:09AM -0700, Chris Horsting wrote:
> > Ken Bloom wrote:
> > > On 2004.07.13 23:12, Chris Horsting wrote:
> > > > Ken Bloom wrote:
> > > > > On 2004.07.13 16:08, Chris Horsting wrote:
> > > > > > Does any one know how to graph polynomial on either octave
> > > > > > or maxima.  There is instruction on graphing trig function
> > > > > > but not polynomials Thanks Chris
> > > > >
> > > > > octave:7> x=-2:.1:2; octave:8> plot(x,x.^2)
> > > > >
> > > > > remember to use operators like .^, .+, .* where you're working
> > > > > with the x matrix, because those do cell-by-cell operations,
> > > > > whereas ^ + and * do matrix operations. (Although it's
> > > > > perfectly OK to write a polynomial as 3*x.^2+3*x+x because +
> > > > > and .+ will be the same, and * is the same as .* when you're
> > > > > multiplying a scalar)
> > > > >
> > > > Hi Ken, I typied the two lines and it did not work. Is there
> > > > another way of defining x?  Thanks Chris
> > > 
> > > Can you show me output and error messages then?
> > > 
> > error: for A^b, A must be square
> > error: evaluating binary operator '^' near line 2, column 9
> > error: evaluating argument list element number 2
> > error: evaluating index expression near line 2, column 1
> 
> You need to use the .^ operator, as I explained above.

Also, look up the POLYVAL function in the documentation.

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