**Advice:**
How many contours?

In
**contourplot**
, the option
**contours=n**
means that if
and
are the maximum and minimum function values on the grid of points that Maple uses for the plot, the contour values are at intervals of length
. Since
and
themselves will generally not correspond to curves on the plot, there will actually be
contours. In
**contourplot3d**
or
**plot3d(..., style=contour)**
, on the other hand, Maple takes the contour values to be integer multiples of a number that is 1, 2 or 5 times a power of 10, using the smallest number of this form that will produce at least
contour values. This was also the behaviour of
**contourplot**
prior to Release 4.

On the other hand, you can use
**contours= [**
a list of values
**]**
, which gives you full control of the values that are plotted.

**Examples:**

`> `
**with(plots,contourplot3d, contourplot):**

Here in
**contourplot3d**
the contour values are multiples of .2, producing 5 contours. In
**contourplot**
, on the other hand, the range 0 to 1 is divided into intervals of length 1/4, and we see 3 contours.

`> `
**contourplot3d(x,x=0..1,y=0..1,contours=4,orientation=[100,90],axes=FRAME);**

`> `
**contourplot(x,x=0..1,y=0..1,contours=4);**

`> `
**contourplot(x,x=0..1,y=0..1,contours=[.2, .4, .6, .8]);**

**See also:**
__contourplot, contourplot3d__
,
__plot3d[options]__

**Maple Advisor Database**
R. Israel, 1997