MATLAB Function Reference
stream2

Compute 2-D stream line 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 stream lines from vector data `u` and `v`. The arrays `x` and `y` define the coordinates for `u` and `v` and must be monotonic and 2-D plaid (such as the data produced by `meshgrid`). `startx` and `starty` define the starting positions of the stream lines. The section Starting Points for Stream Plots in Visualization Techniques provides more information on defining starting points.

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 stream lines. 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 stream line:

• ```[stepsize]
```

or

• ```[stepsize, max_number_vertices]
```

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

• stepsize = 0.1 (one tenth of a cell)
• maximum number of vertices = 10000

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

Examples

This example draws 2-D stream lines 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));
```

`coneplot`, `stream3`, `streamline`