bracketsmacros
I know that in LaTeX newcommand is defined as:
\newcommand{name}[num] {definition }
But I want to define a new command whose argument is not defined between brackets, and it is defined with between \begin and \end commands. For example, something like this:
\teststart bla-bla-bla \testend
Maybe I should define two newcommands, one for \teststart and one for \testend.
I should mention that I have seen such commands in the changebar package,
\cbstart and \cbend.
You cannot have numbers in macro names (at least not without some trickery).
The following works fine:
\documentclass{article}
\usepackage{circuitikz}
\begin{document}
\newcommand\opampfive[5]
{
\begin{circuitikz}
\draw (0,0) node[op amp] (opamp) {};
\draw (-2,-0.49) to[short, o-] (opamp.+) (-2.2,-0.49) node[anchor=east] {${#1}$};
\draw (-2,0.49) to[short, o-] (opamp.-) (-2.2,0.49) node[anchor=east] {${#2}$};
\draw (-0.08,1.5) to[short, o-] (opamp.up) (-0.08,1.6) node[anchor=south] {${#3}$};
\draw (-0.08,-1.5) to[short, o-] (opamp.down) (-0.08,-1.6) node[anchor=north] {${#5}$};
\draw (1,0) to[short, -o] (2,0) -- (opamp.out) (2.1,0) node[anchor=west] {${#4}$};
\end{circuitikz}
}
\opampfive{1}{2}{3}{4}{5}
\end{document}
Here is an alternative to your current situation - using an optional argument to specify the derivative order. This way you don't have to define a macro for "each" derivative:
\deriv[<order>]{<func>}{<var>}
Here's a minimal example:
\documentclass{article}
\newcommand{\deriv}[3][]{% \deriv[<order>]{<func>}{<var>}
\ensuremath{\frac{\partial^{#1} {#2}}{\partial {#3}^{#1}}}}
\begin{document}
In text mode there is~\deriv{y}{x} and~\deriv[2]{y}{x}. In display mode there is
\[
\deriv{y}{x}\ \textrm{and}\ \deriv[2]{y}{x}\rlap{.}
\]
\end{document}
The default <order> is empty, implying the first order partial derivative. If you want the default to be 2, modify the definition to read
\newcommand{\deriv}[3][2]{...}
Technically it is possible to use a macro with numbers in them, but the usage is much less intuitive than adding something like an optional argument (as given above). Here's an implementation that now allows you to use \nameuse{deriv2}{y}{x}:
\expandafter\def\csname deriv2\endcsname#1#2{%
\ensuremath{\frac{\partial^2 {#1}}{\partial {#2}^2}}}
\makeatletter
\newcommand{\nameuse}[1]{\@nameuse{#1}}%
\makeatother
The optional argument beats this hands down.
Best Answer
A higher level possibility is with
xparse:The
+allows the argument to contain blank lines.