contour
Contour plot
`contour(x,y,z)`
`contour(x,y,z,'nolines',numLevels)`
`contour(x,y,z,'nolines',levels)`
`contour(x,y,z,levels)`
`contour(x,y,z,numLevels)`
 Inputs `x` The array of x coordinates of the grid points at which the function is defined. `y` The array of y coordinates of the grid points at which the function is defined. `z` The two dimensional array of the function values at the grid points. `numLevels` The number of levels of the function at which to draw the contour lines. `levels` The array values of levels of the function at which to draw the contour lines. `'nolines'` A flag to suppress the drawing of contour lines.

Description
Draws a contour plot of `z` .

If `x` and `y` are vectors of sizes `n` and `m` , respectively, the `z` should be an `mXn` matrix, with the element `z[i][j]` corresponding to the value of the function at the point `(x[j],y[i]).`

Otherwise, all of the first three of the inputs should be matrices of the same size, with the element `z[i,j]` corresponding to the value of the function at the point `(x[i,j],y[i,j]).`

The latter form of the function call may be used to draw contours of functions with parametric coordinates.

Example
```>>x=[0:.01:1]
>>z=sin(pi*x')*cos(pi*x);
>>subplot(2,1,1);
>>contour(x,x,z)
>>(x,y)=meshgrid(x,x);
>>w=x+i_y;
>>z=w.^.5
>>subplot(2,1,2);
>>contour(real(z),imag(z),abs(z))
```