# ListPlot with Joined set to True

Let

f[x_]=9x^2-2x-3;


I want to make a table of f at x ={-1, -0.5, 0, 0.5, 1, 1.5, 2}. Plot these values with ListPlot + option Joined set to True Make a "normal" plot of f on the interval [-1, 2]

Table[{f[x]}, {x, -1, 2, 0.5}]

Curves := Riffle[Table[{f[x]}, {x, -1, 2, 0.5}], Table[{f[x]}, {x, -1, 2, 0.5}]]
ListLinePlot[Curves]
Plot[f[x], {x, -1, 2}]


Is this ok for this task? Because i think with Joined the points dont get joined but are still separate, but I don't know if that's normal because of ListPlot. And with Plot I don't think I got the right function, but if I do:

Plot[f[x], {x, -1, 2}]


then I miss the points $-.5, .5, 1.5$. Or shouldn't that be a problem since the question is not that specific?

• Is this what you want to do? f[x_] = 9 x^2 - 2 x - 3; Curves = Table[{x, f[x]}, {x, -1, 2, 0.5}]; ListLinePlot[Curves, InterpolationOrder -> 3] Plot[f[x], {x, -1, 2}] – chris Oct 6 '12 at 13:05
• Yes i think it is. – Jaimy Oct 6 '12 at 13:08
• But the next question was: describe the difference of the plots, where i expected listlineplot to be less accurate – Jaimy Oct 6 '12 at 13:08
• remove the InterpolationOrder->3 and it will be so. Interpolation was done precisely to make it look smooth! – chris Oct 6 '12 at 13:11
• ok thanks shouldve come up with that myself... – Jaimy Oct 6 '12 at 13:12

f[x_] = 9 x^2 - 2 x - 3;

which shows the difference between the Built in Plot and ListLinePlot routines.