sl.assemble.eulermatrix: Assemble rotation matrix for Euler angles (z-x-z convention)

In FESOM/spheRlab: Spherical Geometry, Analysis, and Plotting of Geoscientific Data on Arbitrary Grids

Assemble rotation matrix for Euler angles (z-x-z convention)

Description

This function can be used to build the rotation matrix for vector or coordinate rotation by the set of Euler angles which defines the rotation.

Usage

  sl.assemble.eulermatrix(al, be, ga, do.d2r = F)

Arguments

al, be, ga	three numeric scalars defining the Euler angles (in radian).
do.d2r	a logical scalar (default: FALSE), specifying whether the angles are interpreted as radian (FALSE) or degrees (TRUE).

Value

Returns a 3x3 array which can then be used as rotation matrix.

Author(s)

Simon Reifenberg

See Also

sl.rot.vec, sl.rot

Examples

  # note that this example is meant to illustrate how the matrix can be used,
  # the coordinate rotation itself is implemented concisely in sl.rot() 
  
  ### EXAMPLE 
  #   rotate the North Pole to Greenland (-40°E 75°N) - [FESOM standard]
  
  # lon-lat coordinates of North Pole, convert to Cartesian
  NP = c(0,90)                 
  NP.cart = sl.lonlat2xyz(NP)   
  NP.x = NP.cart[1]; NP.y = NP.cart[2]; NP.z = NP.cart[3]
  
  # assemble matrix
  mat = sl.assemble.eulermatrix(50,15,-90, do.d2r=T) 
  
  # matrix multiplication
  NP.x.rot = mat[1,1]*NP.x + mat[1,2]*NP.y + mat[1,3]*NP.z 
  NP.y.rot = mat[2,1]*NP.x + mat[2,2]*NP.y + mat[2,3]*NP.z 
  NP.z.rot = mat[3,1]*NP.x + mat[3,2]*NP.y + mat[3,3]*NP.z 
  
  # convert back to lon-lat coordinates
  NP.rot = sl.xyz2lonlat(x = NP.x.rot, y = NP.y.rot, z = NP.z.rot)
  print(NP.rot)

FESOM/spheRlab documentation built on April 6, 2024, 6:52 p.m.