# Documentation

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# track

Track segments to connect navigational waypoints

## Syntax

```[lattrk,lontrk] = track(waypts) [lattrk,lontrk] = track(waypts,units) [lattrk,lontrk] = track(lat,lon) [lattrk,lontrk] = track(lat,lon,ellipsoid) [lattrk,lontrk] = track(lat,lon,ellipsoid,units,npts) [lattrk,lontrk] = track(method,lat,...) trkpts = track(lat,lon...) ```

## Description

`[lattrk,lontrk] = track(waypts)` returns points in `lattrk` and `lontrk` along a track between the waypoints provided in navigational track format in the two-column matrix `waypts`. The outputs are column vectors in which successive segments are delineated with `NaN`s.

`[lattrk,lontrk] = track(waypts,units)` specifies the units of the inputs and outputs, where `units` is any valid angle unit string. The default is `'degrees'`.

`[lattrk,lontrk] = track(lat,lon)` allows the user to input the waypoints in two vectors, `lat` and `lon`.

`[lattrk,lontrk] = track(lat,lon,ellipsoid)` specifies the shape of the Earth using `ellipsoid`, which can be a `referenceSphere`, `referenceEllipsoid`, or `oblateSpheroid` object, or a vector of the form ```[semimajor_axis eccentricity]```. The default ellipsoid is a unit sphere

`[lattrk,lontrk] = track(lat,lon,ellipsoid,units,npts)` establishes how many intermediate points are to be calculated for every track segment. By default, `npts` is 30.

`[lattrk,lontrk] = track(method,lat,...)` establishes the logic to be used to determine the intermediate points along the track between waypoints. Because this is a navigationally motivated function, the default method is `'rh'`, which results in rhumb line logic. Great circle logic can be specified with `'gc'`.

`trkpts = track(lat,lon...)` compresses the output into one two-column matrix, `trkpts`, in which the first column represents latitudes and the second column, longitudes.

## Examples

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The track function is useful for generating data in order to display tracks. Lieutenant Sextant is the navigator of the USS Neversail. He is charged with plotting a track to take Neversail from the Straits of Gibraltar to Port Said, Egypt, the northern end of the Suez Canal. He has picked appropriate waypoints and now would like to display the track for his captain's approval.

First, display a chart of the Mediterranean Sea.

```load coastlines axesm('mercator','MapLatLimit',[28 47],'MapLonLimit',[-10 37],... 'Grid','on','Frame','on','MeridianLabel','on','ParallelLabel','on') geoshow(coastlat,coastlon,'DisplayType','line','color','b')```

These are the waypoints Lt. Sextant has selected.

`waypoints = [36,-5; 36,-2; 38,5; 38,11; 35,13; 33,30; 31.5,32];`

Now display the track. With a display this clear, the captain gladly approves the plan.

```[lttrk,lntrk] = track('rh',waypoints,'degrees'); geoshow(lttrk,lntrk,'DisplayType','line','color','r')```