Math & Science ⇒ Integral style limits on user-defined commands?

[yakeyglee]

Hey guys,

I just recently defined the following command called \Cint which features an integral sign with a C overlayed (I want to convey a line integral over curve C).

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\newcommand{\Cint}{\mathrlap \int \hspace{1.1px} C \ }

Unfortunately, when I try to put limits on the integral, I find that it behaves just like a regular character, putting them in the standard superscript/subscript positions. For example:

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\Cint_{\vec r_i}^{\vec r_f}

Additionally, I'd like to be able to use the limits command just like you would be able to for a normal integral so that the bounds of integration appear directly above and below the integral sign. The following code outputs an error as the command is currently defined.

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\Cint\limits_{\vec r_i}^{\vec r_f}

What can I change in the definition of \Cint to give me the flexibility of adding limits in the standard way and having them displayed as desired?

--- Trevor

[localghost]

I remember a slightly different notation for the line integral [1]. With your notation you could run into trouble when it comes to calculating the line integral for a closed curve.

However, the command definition is the important part here. That is to say the sequence of the stuff you put in. The \int command has to be the last one in order not to loose the properties for its limits. So, try the below example.

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\documentclass[11pt]{article}

\newcommand{\Cint}{C\kern-1em\int}

\begin{document}
  \[
    \Cint_a^b
  \]
\end{document}

And next time please prepare a proper minimal example. The \mathrlap command is not from vanilla LaTeX and nobody who doesn't know that it is provided by the mathtools package is willing to guess where it comes from.

[1] Line integral – Wikipedia, the free encyclopedia


Thorsten

[yakeyglee]

I remember a slightly different notation for the line integral [1]. With your notation you could run into trouble when it comes to calculating the line integral for a closed curve.

However, the command definition is the important part here. That is to say the sequence of the stuff you put in. The \int command has to be the last one in order not to loose the properties for its limits. So, try the below example.

Code: Select all

\documentclass[11pt]{article}

\newcommand{\Cint}{C\kern-1em\int}

\begin{document}
  \[
    \Cint_a^b
  \]
\end{document}

And next time please prepare a proper minimal example. The \mathrlap command is not from vanilla LaTeX and nobody who doesn't know that it is provided by the mathtools package is willing to guess where it comes from.

[1] Line integral – Wikipedia, the free encyclopedia


Thorsten

For closed curve line integrals, I'd just use the typical notation.

Code: Select all

\oint_C

I made the new notation for the other so I could specify bounds without having the lower bound confused with the curve of integration.

Thanks for the help.