MATLAB Function Reference |

**Syntax**

**Description**

A pseudocolor plot is a rectangular array of cells with colors determined by `C`

. MATLAB creates a pseudocolor plot using each set of four adjacent points in `C`

to define a surface rectangle (i.e., cell).

The default `shading`

is `faceted`

, which colors each cell with a single color. The last row and column of `C`

are not used in this case. With `shading`

`interp`

, each cell is colored by bilinear interpolation of the colors at its four vertices, using all elements of `C`

.

The minimum and maximum elements of `C`

are assigned the first and last colors in the colormap. Colors for the remaining elements in `C`

are determined by a linear mapping from value to colormap element.

```
pcolor(C)
```

draws a pseudocolor plot. The elements of `C`

are linearly mapped to an index into the current colormap. The mapping from `C`

to the current colormap is defined by `colormap`

and `caxis`

.

```
pcolor(X,Y,C)
```

draws a pseudocolor plot of the elements of `C`

at the locations specified by `X`

and `Y`

. The plot is a logically rectangular, two-dimensional grid with vertices at the points `[X(i,j),`

`Y(i,j)]`

. `X`

and `Y`

are vectors or matrices that specify the spacing of the grid lines. If `X`

and `Y`

are vectors, `X`

corresponds to the columns of `C`

and `Y`

corresponds to the rows. If `X`

and `Y`

are matrices, they must be the same size as `C`

.

```
pcolor(axes_handles,...)
```

plots into the axes with handle `axes_handle`

instead of the current axes (`gca`

).

```
h = pcolor(...)
```

returns a handle to a surface graphics object.

**Remarks**

A pseudocolor plot is a flat surface plot viewed from above. `pcolor(X,Y,C)`

is the same as viewing `surf`

`(X,Y,0*Z,C)`

using `view([0 90])`

.

When you use `shading`

`faceted`

or `shading`

`flat`

, the constant color of each cell is the color associated with the corner having the smallest *x*-*y* coordinates. Therefore, `C(i,j)`

determines the color of the cell in the *i*th row and *j*th column. The last row and column of `C`

are not used.

When you use `shading interp`

, each cell's color results from a bilinear interpolation of the colors at its four vertices, and all elements of `C`

are used.

**Examples**

A Hadamard matrix has elements that are `+1`

and `-1`

. A colormap with only two entries is appropriate when displaying a pseudocolor plot of this matrix.

A simple color wheel illustrates a polar coordinate system.

n = 6; r = (0:n)'/n; theta = pi

`*`

(-n:n)/n; X = r`*`

cos(theta); Y = r`*`

sin(theta); C = r*cos(2*theta); pcolor(X,Y,C) axis equal tight

**Algorithm**

The number of vertex colors for `pcolor(C)`

is the same as the number of cells for `image(C)`

.` pcolor`

differs from `image`

in that `pcolor(C)`

specifies the colors of vertices, which are scaled to fit the colormap; changing the axes `clim`

property changes this color mapping. `image(C)`

specifies the colors of cells and directly indexes into the colormap without scaling. Additionally, `pcolor(X,Y,C)`

can produce parametric grids, which is not possible with `image`

.

**See Also**

`caxis`

, `image`

, `mesh`

, `shading`

, `surf`

, `view`

pcode | pdepe |

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