function [rz] = initializeRz(args)

  arguments
    args.type    char    {mustBeMember(args.type,{'none', 'rigid', 'flexible', 'modal-analysis', 'init'})} = 'flexible'
    args.Foffset logical {mustBeNumericOrLogical} = false
  end

  rz = struct();

  switch args.type
    case 'none'
      rz.type = 0;
    case 'rigid'
      rz.type = 1;
    case 'flexible'
      rz.type = 2;
    case 'modal-analysis'
      rz.type = 3;
    case 'init'
      rz.type = 4;
  end

  % Spindle - Slip Ring
  rz.slipring.density = 7800; % [kg/m3]
  rz.slipring.STEP    = 'Spindle_Slip_Ring.STEP';

  % Spindle - Rotor
  rz.rotor.density    = 7800; % [kg/m3]
  rz.rotor.STEP       = 'Spindle_Rotor.STEP';

  % Spindle - Stator
  rz.stator.density   = 7800; % [kg/m3]
  rz.stator.STEP      = 'Spindle_Stator.STEP';

  rz.K = [7e8; 7e8; 2e9; 1e7; 1e7; 1e7];
  rz.C = [4e4; 4e4; 7e4; 1e4; 1e4; 1e4];

  if args.Foffset && ~strcmp(args.type, 'none') && ~strcmp(args.type, 'rigid') && ~strcmp(args.type, 'init')
    load('Foffset.mat', 'Fzm');
    rz.Deq = -Fzm'./rz.K;
  else
    rz.Deq = zeros(6,1);
  end

if exist('./mat', 'dir')
    if exist('./mat/nass_stages.mat', 'file')
        save('mat/nass_stages.mat', 'rz', '-append');
    else
        save('mat/nass_stages.mat', 'rz');
    end
elseif exist('./matlab', 'dir')
    if exist('./matlab/mat/nass_stages.mat', 'file')
        save('matlab/mat/nass_stages.mat', 'rz', '-append');
    else
        save('matlab/mat/nass_stages.mat', 'rz');
    end
end