~ in latex

2019-12-02 17:32发布

I see a latex code ```latex{ ~~~~a) squared difference: \begin{equation} \label{eq.square_diff} ...

I see a latex code ```latex{ ~~~~a) squared difference: \begin{equation} \label{eq.square_diff} \Phi(q_{\mathbf{p}'}, k_{\mathbf{p}}) = -( q_{\mathbf{p}'} - k_{\mathbf{p}})^2. \end{equation} ``` But I don't know the meaning of "\~\~\~\~" in the code?