# sl.lonlatrot2abg: Convert Rotation Lon-Lat-Rot to Alpha-Beta-Gamma In helgegoessling/spheRlab: Spherical Geometry, Analysis, and Plotting of Geoscientific Data on Arbitrary Grids

## Description

Convert rotation parameters from longitude-latitude-rotation to alpha-beta-gamma.

## Usage

 `1` ```sl.lonlatrot2abg(lonlatrot) ```

## Arguments

A vector of length 3 with the following elements:

 `lonlatrot[1]` The longitude of the point that is supposed to be the new North Pole. `lonlatrot[2]` The latitude of the point that is supposed to be the new North Pole. `lonlatrot[3]` The angle (in degrees) of rotation around the new North Pole.

## Value

A vector of length 3 with the parameters alpha, beta, and gamma as used in `sl.rot`. Note that to achieve identity transformation (that is, no transformation at all) the third element of the argument must be `-90` (see the second example).

## Author(s)

Helge Goessling

`sl.rot`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23``` ```abg = sl.lonlatrot2abg(lonlatrot=c(30,0,5)) sl.rot(lon=0,lat=0,alpha=abg[1],beta=abg[2],gamma=abg[3]) ## Should return: ## \$lon ## [1] 175 ## ## \$lat ## [1] 60 sl.rot(lon=30,lat=0,alpha=abg[1],beta=abg[2],gamma=abg[3]) ## Should return: \$lon ## [1] -20.55605 ## ## \$lat ## [1] 90 abg = sl.lonlatrot2abg(lonlatrot=c(0,90,-90)) sl.rot(lon=-150,lat=40,alpha=abg[1],beta=abg[2],gamma=abg[3]) ## Should return: ## \$lon ## [1] -150 ## ## \$lat ## [1] 40 ```