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\newcommand{\cis}[1]{\hbox{\rm cis}\left(#1\right)}
\newcommand{\cisl}[1]{\cos\left(#1\right) +
                      i \sin\left(#1\right)}
\newcommand{\ccis}[1]{\hbox{\rm cis}^*\left(#1\right)}
\newcommand{\ccisl}[1]{\cos\left(#1\right) - 
                       i \sin\left(#1\right)}
\newcommand{\cas}[1]{\hbox{\rm cas}\left(#1\right)}
\newcommand{\casl}[1]{\cos\left(#1\right) + \sin\left(#1\right)}
\newcommand{\conv}{\,\rlap{$\circ$}\ast}
\newcommand{\shah}{{\rm I \! I \! I}}
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\newcommand{\step}{{\vrule height.4pt width2pt depth0pt
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                                    ^{\frac{#2_1}{2}}
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                                    ^{\frac{#2_2}{2}}}
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\newcommand{\ftran}{\stackrel{\cal F}{\longleftrightarrow}}
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