Math & Science ⇒ Error in Code for Math Expression

[unknown]

Hi,

I'm trying to render maths like this.

Code: Select all

$\text{SPRT}{}_{j=1\sim4}=\sum\limits_{s=i}^{k}\ln\left(\frac{\fint_{j}\left(\chi_{s}\right)}{\fint_{0}\left(\chi_{s}\right)}\right)$

I cannot find the error. Compilation problem is:

Code: Select all

! Undefined control sequence.

Any help is appreciated!

[cgnieder]

Hi unknown,

welcome to the LaTeX community.

Hi, I'm trying to render maths as

$\text{SPRT}{}_{j=1\sim4}=\sum\limits_{s=i}^{k}\ln\left(\frac{\fint_{j}\left(\chi_{s}\right)}{\fint_{0}\left(\chi_{s}\right)}\right)$

and I cannot find the error. Compilation problem is: ! Undefined control sequence. Please help!

Without a minimal working example it is not really possible to tell as we can't know which packages you're using or not. I don't know the control sequence \fint for example... all the other ones are defined if you load amsmath.

Code: Select all

\documentclass{article}
\usepackage{amsmath}
% no idea what \fint should be. I'm defining it to be `f':
\newcommand\fint{f}
\begin{document}


\[
  \text{SPRT}{}_{j=1\sim4}
   =
  \sum\limits_{s=i}^{k}\ln\left(
    \frac
      {\fint_{j}\left(\chi_{s}\right)}
      {\fint_{0}\left(\chi_{s}\right)}
  \right)
\]

\end{document}

Regards

[unknown]

Thanks a lot, \fint is the answer. Everything works now. I really do not know where I found that \fint.

[localghost]

[…] I really do not know where I found that \fint.

Perhaps in »The Comprehensive LaTeX Symbol List«.


Best regards and welcome to the board
Thorsten