Documentation

### This is machine translation

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

Note: This page has been translated by MathWorks. Click here to see
To view all translated materials including this page, select Country from the country navigator on the bottom of this page.

# stream2

Compute 2-D streamline data

## Syntax

```XY = stream2(x,y,u,v,startx,starty) XY = stream2(u,v,startx,starty) XY = stream2(...,options) ```

## Description

`XY = stream2(x,y,u,v,startx,starty) ` computes streamlines from vector data `u` and `v`.

The arrays `x` and `y`, which define the coordinates for `u` and `v`, must be monotonic, but do not need to be uniformly spaced. `x` and `y` must have the same number of elements, as if produced by `meshgrid`.

`startx` and `starty` define the starting positions of the streamlines.

The returned value `XY` contains a cell array of vertex arrays.

`XY = stream2(u,v,startx,starty) ` assumes the arrays `x` and `y` are defined as `[x,y] = meshgrid(1:n,1:m)` where ```[m,n] = size(u)```.

`XY = stream2(...,options) ` specifies the options used when creating the streamlines. Define `options` as a one- or two-element vector containing the step size or the step size and the maximum number of vertices in a streamline:

```[stepsize] ```

or

```[stepsize, max_number_vertices] ```

If you do not specify a value, MATLAB® software uses the default:

• Step size = 0.1 (one tenth of a cell)

• Maximum number of vertices = 10000

Use the `streamline` command to plot the data returned by `stream2`.

## Examples

collapse all

Plot 2-D streamlines from data representing air currents over regions of North America.

```load wind [sx,sy] = meshgrid(80,20:10:50); streamline(stream2(x(:,:,5),y(:,:,5),u(:,:,5),v(:,:,5),sx,sy));``` Download ebook