Optic_flow_RF_estimation_Zhang_et_al_2022/code/OpticflowFitting/mixflow_LS_optimization.m

function ssr=mixflow_LS_optimization(coef,flowfield)
  flowfield_pos = flowfield(:,1);
  flowfield_vec = flowfield(:,2);
  valid_flowfield_idx = norm(flowfield_vec)>0;
  
  rot_axis  = normalize(floQ(coef(1,2:4)));
  rot_scale = coef(1,1);
  fit_rotField = -rot_axis.Qcross(flowfield_pos).*rot_scale; % Rotation Field
  
  trans_axis = normalize(floQ(coef(2,2:4)));
  trans_scale = coef(2,1);
  fit_transField = (trans_axis+flowfield_pos.*trans_axis.*flowfield_pos)./2.*trans_scale; % Translational Field

  fit_mixField = fit_transField+fit_rotField;
  residue= fit_mixField(valid_flowfield_idx).Qangle(flowfield_vec(valid_flowfield_idx));
  ssr = sum(residue.^2);