%
%   dmath.sty
%
%  following commands are defined
%
%  \DD[n]{A}{x}
%  \DP[n][y]{A}{x}
%  \Dvect{v}
%  \Dinv{A}
%  \Dgrad{A}
%  \Ddiv{A}
%  \Drot{A}
%  \Dnablagrad
%  \Dchargrad
%
\def\DD{\@ifnextchar [{\D@D}{\D@D[]}}
\def\D@D[#1]#2#3{\frac{d^{#1} #2}{d #3{}^{#1}}}
\def\DP{\@ifnextchar [{\D@P}{\D@P[]}}
\def\D@P[#1]{\@ifnextchar [{\D@Pi[#1]}{\D@PD[#1]}}
\def\D@PD[#1]#2#3{\frac{\partial^{#1} #2}{\partial #3{}^{#1}}}
\def\D@Pi[#1][#2]#3#4{\left( \frac{\partial^{#1} #3}{\partial #4{}^{#1}}
                      \right)_{#2}}
%
\def\Dvect#1{\mbox{\boldmath $#1$}}
\def\Dinv#1{\frac{1}{#1}}
\def\Dlapla{\@ifnextchar [{\D@lapla} % ]
           {\D@lapla[2]}}
\def\D@lapla[#1]{\nabla^{#1}}
\def\D@ngrad{\nabla}
\def\D@ndiv{\nabla \cdot}
\def\D@nrot{\nabla \times}
\def\D@cgrad{\mbox{grad}}
\def\D@cdiv{\mbox{div}}
\def\D@crot{\mbox{rot}}
\def\Dnablagrad{\let\Dgrad\D@ngrad \let\Ddiv\D@ndiv \let\Drot\D@nrot}
\def\Dchargrad{\let\Dgrad\D@cgrad \let\Ddiv\D@cdiv \let\Drot\D@crot}
%
\def\Dd{\,d}
\def\Ddint{\int\!\!\!\int}
\def\Dtint{\int\!\!\!\int\!\!\!\int}
\def\Ddsty{\displaystyle}
%
\Dnablagrad
