R/invembeddingR6_vecs.R

In mrparker909/MGLMRiem: Multivariate Generalized Linear Models on Riemannian Manifolds

# function Vnew = invembeddingR6_vecs(p, V)
# %INVEMBEDDINGR6_VECS is the inverse of EMBEDDINGR6_VECS. This brings V in R6 to in TpM.
# %This transports V from T_{I}M to TpM.
# %
# %   This will be replaced later with the group action for n x n spd matrix and a proper vectorization. 
# %    
# %   Vnew = EMBEDDINGR6_VECS(p,V)
# %
# %   p is a base point. 
# %   Vnew is a set of tangent vectors in TpM.
# %   V is a set of vectors in R6.
# %
# %   See also INVEMBEDDINGR6, EMBEDDINGR6_VECS, EMBEDDINGR6
# 
# %   Hyunwoo J. Kim
# %   $Revision: 0.1 $  $Date: 2014/06/23 15:32:53$ 
#   
#   %    v = [Sxx Sxy Sxz Syy Syz Szz]';    
# 
# if size(V,2) == 1
#     Vnew = invembeddingR6(p, V);
#     return;
# elseif length(size(V)) == 2
#     nmx = size(V, 2);
#     Vnew = zeros(3,3, nmx);
#     for i=1:nmx
#         Vnew(:,:,i) = invembeddingR6(p, V(:,i));
#     end
# else
#     error('V is wrong input');
# end

#' @export
invembeddingR6_vecs <- function(p, V) {
#INVEMBEDDINGR6_VECS is the inverse of EMBEDDINGR6_VECS. This brings V in R6 to in TpM.
#This transports V from T_{I}M to TpM.
#
#   This will be replaced later with the group action for n x n spd matrix and a proper vectorization. 
#
#   Vnew = EMBEDDINGR6_VECS(p,V)
#
#   p is a base point. 
#   Vnew is a set of tangent vectors in TpM.
#   V is a set of vectors in R6.
#
#   See also INVEMBEDDINGR6, EMBEDDINGR6_VECS, EMBEDDINGR6

#   Hyunwoo J. Kim
#   $Revision: 0.1 $  $Date: 2014/06/23 15:32:53$ 

#   Migrated to R by Matthew RP Parker
#   $Revision: 0.2 $  $Date: 2019/06/17 $ 

#    v = [Sxx Sxy Sxz Syy Syz Szz]';    
    
    if(sizeR(V,2) == 1) {
      Vnew = invembeddingR6(p, V)
    } else if(length(sizeR(V)) == 2) {
      nmx = sizeR(V, 2)
      Vnew = array(0, dim=c(3,3, nmx))
      for(i in 1:nmx) {
        Vnew[,,i] = invembeddingR6(p, v = V[,i])
      }
    } else {
      stop('V is wrong input')
    }
    return(Vnew)
}