Y00 can often make a contour plot communicate more effectively by using different colors to represent different values of z. Alternatively, if you intend to print on a black and white printer, you can achieve a similar effect by using different shades of gray to represent different values of z. Use the Color and Lines page of the 3D Plot Format dialog box.
To specify the shading of your plot, click the appropriate button in the Shading group:
• Color: The bands between contour lines are colored. The largest values of the matrix will be in red and the smallest values will be in blue. Intermediate values will range from yellow through green.
• None: The bands between contour lines don’t have any shading. Be sure the Contour Lines check box is checked or you won’t see any contours at all.
• Grayscale: The bands between contour lines are in shades of gray. The largest values of the matrix will be in white and the smallest values will be in black. Intermediate values will be in shades of gray.
The same contour plot displayed without shading and in grayscale.
Besides varying the colors of a contour plot, you can also choose to hide-the contours themselves. If you’ve chosen to leave the surface without shading (“None”), you should have the contour lines showing. If the plot is colored or grayscale, you can hide the contour lines and let the colors or gray shades show the contours. To show or hide the contour lines, click Contour Lines to add or remove the checkmark. The same contour plot with the contour lines hidden and showing. Contours can be numbered to indicate the value associated with that contour. To add or remove numbers on most contours, use the Numbered check box. Figure 23-4 shows the same contour plot with numbered and unnumbered contour lines. Note that Mathcad doesn’t number every contour when to do so would result in overcrowding.
To haye Mathcad automatically select the number of contours to display, use the Auto Contour check box. When checked, Mathcad will automatically select the number of contours. When unchecked, you select the number of contours. To specify the number of contours, enter an integer into the No. of Contours text box. This text box is only available when Auto Contour is unchecked. Figure 23-4 shows the same contour plot with contours automatically selected by Mathcad and with a specified number of contours.