Filled 2-D contour plot
[C,h] = contourf(...)
A filled contour plot displays isolines calculated from matrix Z and fills the areas between the isolines using constant colors corresponding to the current figure's colormap.
contourf(Z) draws a filled contour plot of matrix Z, where Z is interpreted as heights with respect to the x-y plane. Z must be at least a 2-by-2 matrix that contains at least two different values. The x values correspond to the column indices of Z and the y values correspond to the row indices of Z. The contour levels are chosen automatically.
contourf(Z,v) draws a filled contour plot of matrix Z with contour lines at the data values specified in the monotonically increasing vector v. To display a single contour line at a particular value, define v as a two-element vector with both elements equal to the desired contour level. For example, to draw a single contour of level k, use contourf(Z,[k k]). Specifying the vector v sets the LevelListMode property to manual.
If X and Y are vectors, then length(X) must equal size(Z,2) and length(Y) must equal the number of rows in size(Z,1). The vectors must be strictly increasing or strictly decreasing and cannot contain any repeated values.
If X and Y are matrices, then their sizes must equal the size of Z. Typically, you should set X and Y so that the columns are strictly increasing or strictly decreasing and the rows are uniform (or the rows are strictly increasing or strictly decreasing and the columns are uniform).
If X or Y is irregularly spaced, then contourf calculates contours using a regularly spaced contour grid, and then transforms the data to X or Y.
contourf(...,LineSpec) draws the contour lines using the line type and color specified by LineSpec. contourf ignores marker symbols.
contourf(...,Name,Value) specifies contour properties using one or more property name, property value pairs. Name is the property name and must appear inside single quotes (''). Value is the corresponding value. For example, 'LineWidth',2 sets the contour line width to 2. For a list of contour property names and values, see Contour Properties.
contourf(ax,...) plots into the axes specified by ax instead of into the current axes (gca).
[C,h] = contourf(...) returns the contour matrix C containing the data that defines the contour lines and a contour object h. The ContourMatrix property for the contour object also contains the contour matrix. The clabel function uses the contour matrix to label the contour lines.