check_gradient: changed gradient and conditioner product to element wise product (caused Eigen assert)
check_gradient: changed gradient and conditioner product to element wise product (caused Eigen assert)

MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3