;+
; NAME:
;  extract_last
; PURPOSE: (one line)
;  Pull out a scalar or array from a scalar or 1 or 2-D array
; DESCRIPTION:
;  Pull out a scalar or array from a scalar or 1 or 2-D array
;  given an index into the last dimension of the input
; CATEGORY:
;  Utility
; CALLING SEQUENCE:
;  arr_k = extract_last(mat) 
; INPUTS:
;   mat - scalar, [n_last], [n_other,n_last]
; OUTPUTS:
;   If mat is a scalar, return mat (scalar)
;   If mat is an array, return mat[k] (scalar)
;   If mat is 2-D, return mat[*,k] (1-D)
; OPTIONAL OUTPUTS:
;   dim - number of dimensions for mat
;   n_last - length of the last dimension
; MODIFICATION HISTORY:
;  Written 2012 Jan 9, by Leslie Young, SwRI
;  2016 Mar 23 LAY.  Edited documentation and move into layoung library
;-
function extract_last,mat,k,dim, n_last

    dim = size(mat, /n_dim)
    n_last=n_elements(mat)
    case dim of
       0: return, mat
       1: return, mat[k]
       2: begin
          n_last = n_elements(mat[0,*])
          return, mat[*,k]
       end
    endcase

 end