Documentation

### This is machine translation

Mouseover text to see original. Click the button below to return to the English version of the page.

To view all translated materials including this page, select Country from the country navigator on the bottom of this page.

# surfc

Contour plot under a 3-D shaded surface plot ## Syntax

```surfc(Z) surfc(Z,C) surfc(X,Y,Z) surfc(X,Y,Z,C) surfc(...,'PropertyName',PropertyValue) surfc(axes_handles,...) h = surfc(...) ```

## Description

`surfc(Z)` creates a contour plot under the three-dimensional shaded surface from the z components in matrix `Z`, using `x` `=` `1:n` and `y` `=` `1:m`, where `[m,n] = size(Z)`. The height, `Z`, is a single-valued function defined over a geometrically rectangular grid. `Z` specifies the color data, as well as surface height, so color is proportional to surface height.

`surfc(Z,C)` plots the height of `Z`, a single-valued function defined over a geometrically rectangular grid, and uses matrix `C`, assumed to be the same size as `Z`, to color the surface.

`surfc(X,Y,Z)` uses `Z` for the color data and surface height. `X` and `Y` are vectors or matrices defining the `x` and `y` components of a surface. If `X` and `Y` are vectors, `length(X)` `=` `n` and `length(Y)` `=` `m`, where `[m,n]` `=` `size(Z)`. In this case, the vertices of the surface faces are (X(j), Y(i), Z(i,j)) triples. To create X and Y matrices for arbitrary domains, use the `meshgrid` function.

`surfc(X,Y,Z,C)` uses `C` to define color. MATLAB® performs a linear transformation on this data to obtain colors from the current colormap.

`surfc(...,'PropertyName',PropertyValue)` specifies surface properties along with the data.

`surfc(axes_handles,...)` plots into the axes with handle `axes_handle` instead of the current axes (`gca`).

`h = surfc(...)` returns handles to a chart surface and a contour object.

## Examples

collapse all

Display a contour plot under a surface plot of the `peaks` function.

```[X,Y,Z] = peaks(30); figure surfc(X,Y,Z)``` ## Tips

`surfc` does not accept complex inputs.

## Algorithms

Consider a parametric surface parameterized by two independent variables, `i` and `j`, which vary continuously over a rectangle; for example, `1``i``m` and `1``j``n`. The three functions `x(i,j)`, `y(i,j)`, and `z(i,j)` specify the surface. When `i` and `j` are integer values, they define a rectangular grid with integer grid points. The functions `x(i,j)`, `y(i,j)`, and `z(i,j)` become three `m`-by-`n` matrices, `X`, `Y`, and `Z`. Surface color is a fourth function, `c(i,j)`, denoted by matrix `C`.

Each point in the rectangular grid can be thought of as connected to its four nearest neighbors.

``` i-1,j | i,j-1 - i,j - i,j+1 | i+1,j ```

This underlying rectangular grid induces four-sided patches on the surface. To express this another way, `[X(:)` `Y(:)` `Z(:)]` returns a list of triples specifying points in 3-D space. Each interior point is connected to the four neighbors inherited from the matrix indexing. Points on the edge of the surface have three neighbors. The four points at the corners of the grid have only two neighbors. This defines a mesh of quadrilaterals or a quad-mesh.

You can specify surface color in two different ways: at the vertices or at the centers of each patch. In this general setting, the surface need not be a single-valued function of `x` and `y`. Moreover, the four-sided surface patches need not be planar. For example, you can have surfaces defined in polar, cylindrical, and spherical coordinate systems.

The `shading` function sets the shading. If the shading is `interp`, `C` must be the same size as `X`, `Y`, and `Z`; it specifies the colors at the vertices. The color within a surface patch varies depending on the color at the local coordinates. If the shading is `faceted` (the default) or `flat`, `C(i,j) `specifies the constant color in the surface patch:

``` (i,j) - (i,j+1) | C(i,j) | (i+1,j) - (i+1,j+1) ```

In this case, `C` can be the same size as `X`, `Y`, and `Z` and its last row and column are ignored. Alternatively, its row and column dimensions can be one less than those of `X`, `Y`, and `Z`.

The `surfc` function specifies the viewpoint using `view(3)`.

The range of `X`, `Y`, and `Z` or the current setting of the axes `XLimMode`, `YLimMode`, and `ZLimMode` properties (also set by the `axis` function) determines the axis labels.

The range of `C` or the current setting of the axes `CLim` and `CLimMode` properties (also set by the `caxis` function) determines the color scaling. The scaled color values are used as indices into the current colormap.