polyarea

Area of polygon

Syntax

a = polyarea(x,y)

a = polyarea(x,y,dim)

Description

a = polyarea(x,y) returns the area of the 2-D polygon defined by the vertices in vectors x and y.

• If x and y are vectors of the same length, then polyarea returns the scalar area of the polygon defined by x and y.

• If x and y are matrices of the same size, then polyarea returns a row vector containing the areas of each polygon defined by the columnwise pairs in x and y.

• If x and y are multidimensional arrays, then polyarea operates along the first dimension whose length is not equal to 1.

a = polyarea(x,y,dim) operates along dimension dim.

Examples

Area of Polygon

Create a set of points that define a 2-D polygon.

p = linspace(0,2.*pi,9);
x = 1.2*cos(p)';
y = 1.2*sin(p)'; 

Plot the polygon.

plot(x,y);
axis equal

Compute the area of the polygon.

a = polyarea(x,y)

a = 
4.0729

Input Arguments

x — x-coordinates

vector | matrix | multidimensional array

x-coordinates, specified as a vector, matrix, or multidimensional array.

y — y-coordinates

vector | matrix | multidimensional array

y-coordinates, specified as a vector, matrix, or multidimensional array.

dim — Dimension

positive integer scalar

Dimension to operate along, specified as a positive integer scalar.

Tips

• The area value returned by polyarea can depend on the order of the input points.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

The polyarea function fully supports GPU arrays. To run the function on a GPU, specify the input data as a gpuArray (Parallel Computing Toolbox). For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).

Version History

Introduced before R2006a