1
$\begingroup$

When use the following command to plot a graph

Plot[x^(1/3), {x, -1, 1}]

figure

Mathematica does not show the range [0, 1]. It does not show the range [-1, 0]. While for function 1/x it does.

Plot[1/x, {x, -1, 1}]

figure

How can I make Mathematica show the range specified for x^(1/3) ?

$\endgroup$
  • 1
    $\begingroup$ It doesn't plot imaginary numbers (such as the root of a negative number) because the plot coordinate system is over the real cartesian 2D space. You can use Re to obtain the real component and plot that. $\endgroup$ – C. E. Jul 4 '15 at 21:30
  • 2
    $\begingroup$ There's also CubeRoot and Surd for real-valued functions. $\endgroup$ – Michael E2 Jul 4 '15 at 22:19
  • 1
    $\begingroup$ The problem is not with Plot but with the cube root itself. See Finding real roots of negative numbers. $\endgroup$ – Rahul Jul 4 '15 at 22:51
  • 1
    $\begingroup$ I'm voting to close this question as off-topic because the issue it raises is not a Mathematica issue but a mathematics one. $\endgroup$ – m_goldberg Jul 4 '15 at 23:09
2
$\begingroup$
Plot[{Re[x^(1/3)], Im[x^(1/3)]}, {x, -1, 1}]

or plotting the modulus:

Plot[Abs[x^(1/3)], {x, -1, 1}]
$\endgroup$
  • 1
    $\begingroup$ With PlotRange->Full, Mathematica still only show the positive range. (I use Mathematica 9.) $\endgroup$ – Ben Wu Jul 4 '15 at 21:40

Not the answer you're looking for? Browse other questions tagged or ask your own question.