R: Inverse Geodesic Calculation

geodXyInverse {oce} | R Documentation

## Inverse Geodesic Calculation

### Description

The calculation is done by finding a minimum value of a cost function that is the vector difference between (`x`,`y`) and the corresponding values returned by `geodXy`. See “Caution”.

### Usage

    geodXyInverse(x, y, longitudeRef, latitudeRef,
      debug = getOption("oceDebug"))

### Arguments

`x` | value of x in metres, as given by `geodXy`
`y` | value of y in metres, as given by `geodXy`
`longitudeRef` | reference longitude, as supplied to `geodXy`
`latitudeRef` | reference latitude, as supplied to `geodXy`
`debug` | an integer specifying whether debugging information is to be printed during the processing. This is a general parameter that is used by many `oce` functions. Generally, setting `debug=0` turns off the printing, while higher values suggest that more information be printed. If one function calls another, it usually reduces the value of `debug` first, so that a user can often obtain deeper debugging by specifying higher `debug` values.

### Details

The minimum is calculated in C for speed, using the `nmmin` function that is the underpinning for the Nelder-Meade version of the R function `optim`. If you find odd results, try setting `debug=1` and rerunning, to see whether this optimizer is having difficulty finding a minimum of the mismatch function.

### Value

a data frame containing `longitude` and `latitude`

### Caution

This scheme is without known precedent in the literature, and users should read the documentation carefully before deciding to use it.

### See Also

Other functions relating to geodesy: `geodDist`, `geodGc`, `geodXy`

[Package oce version 1.1-1 Index]