# Reverts speed and direction to U and V components.

### Description

This function calculates U (i.e. zonal or east/west) and V (i.e. meridional or north/south) components from a specified speed and direction.

### Usage

1 | ```
NCEP.uv.revert(spd, dir, radians=FALSE)
``` |

### Arguments

`spd` |
A numeric value indicating speed. |

`dir` |
A numeric value indicating direction in degrees from north or radians if |

`radians` |
A logical indicating whether |

### Details

This function calculates U (i.e. zonal or east/west) and V (i.e. meridional or north/south) components from a specified speed and direction. U and V components describe the direction into which movement occurs with east and north being positive, respectively. If directions are given in radians, `radians`

must be set to `TRUE`

.

### Value

A `data.frame`

containing U and V components given in the same units as `speed`

.

### Author(s)

Michael U. Kemp mukemp+RNCEP@gmail.com

### References

**To cite package 'RNCEP' in publications use:**

Kemp, M. U., van Loon, E. E., Shamoun-Baranes, J., and Bouten, W. 2011. RNCEP:global weather and climate data at your fingertips. – Methods in Ecology and Evolution. DOI:10.1111/j.2041-210X.2011.00138.x.

### Examples

1 2 3 | ```
library(RNCEP)
## Using NCEP.uv.revert ##
NCEP.uv.revert(spd=12, dir=225, radians=FALSE)
``` |