Error, (in plot/iplot2d/levelcurve) could not evaluate expression - Maple Programming Help

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Error, (in plot/iplot2d/levelcurve) could not evaluate expression

 Description This error occurs if Maple cannot evaluate the given expression to a numeric value when graphing with plots[contourplot].

Examples

 > $\mathrm{with}\left(\mathrm{plots}\right):$

Example 1

In this example, the wrong variable is used in the expression to be plotted.

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Solution:

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Example 2

In the following example, the first argument passed to contourplot is a complex value, instead of a real value.

 > $\mathrm{contourplot}\left(x+I\cdot y,x=-3..3,y=-3..3\right)$

Solution:

To correct the error, pass only the real part of the complex value as an argument to contourplot.

 > $\mathrm{contourplot}\left(\mathrm{Re}\left(x+I\cdot y\right),x=-3..3,y=-3..3\right)$