Chenghao He

the underline in equation is replaced by *

1

I find the equation: ``` $$ \mathbf{L}_{\mathbf{X}}\chi_{xx^{\prime}}^{-1} $$ ``` $$ L_{X}\chi_{xx^{\prime}}^{-1} $$ will be turned into ``` $$ \mathbf{L}*{\mathbf{X}}\chi*{xx^{\prime}}^{-1} $$ ``` $$ L*{X} \chi*{xx^{\prime}}^{-1} $$