Graphs a 3-D surface.


This function is for use with the deprecated PQG graphics. Use plotSurface() instead.




surface(x, y, z)
  • x (1xK vector) – the x-axis data.
  • y (Nx1 vector) – the y-axis data.
  • z (NxK matrix) – the matrix of height data to be plotted.

Global Input


2x1 vector, controls 3-D surface characteristics.

[1]:if 1, show hidden lines. Default 0.
[2]:color for base (default 7). The base is an outline of the X-Y plane with a line connecting each corner to the surface. If 0, no base is drawn.

scalar, if 0 (default), tick marks point inward, if 1, tick marks point outward.


Z level color control.

There are 3 ways to set colors for the Z levels of a surface graph.

  1. To specify a single color for the entire surface plot, set the color

    control variable to a scalar value 1-15. For example:

    _pzclr = 15;
  2. To specify multiple colors distributed evenly over the entire Z range,

    set the color control variable to a vector containing the desired colors only. GAUSS will automatically calculate the required corresponding Z values for you. The following example will produce a three color surface plot, the Z ranges being lowest=blue, middle=light blue, highest=white:

    _pzclr = { 1, 10, 15 };
  3. To specify multiple colors distributed over selected ranges, the Z

    ranges as well as the colors must be manually input by the user. The following example assumes -0.2 to be the minimum value in the z matrix:

    _pzclr = { -0.2 1,
    /* z >= -0.2 blue */
     0.0 10,
    /* z >= 0.0 light blue */
     0.2 15 };
    /* z >= 0.2 white */

    Since a Z level is required for each selected color, the user must be responsible to compute the minimum value of the z matrix as the first Z range element. This may be most easily accomplished by setting the _pzclr matrix as shown above (the first element being an arbitrary value), then resetting the first element to the minimum z value as follows:

    _pzclr = { 0.0 1,
               0.0 10,
               0.2 15 };
    _pzclr[1,1] = minc(minc(z));

See PQG Graphics Colors, for the list of available colors.


surface() uses only the minimum and maximum of the x-axis data in generating the graph and tick marks.



See also

Functions volume(), view()