latex undefined control sequence with tableofcontents

I was using \documentclass{amsmath} for awhile with no issues, but I recently wanted to switch to the normal \documentclass{article} because I thought it looked nicer. However, now my \tableofcontents command produces this error:

! Undefined control sequence.
<argument> \tocsecti开发者_C百科on 
                       {}{1}{Purpose}
l.1 ...ne {section}{\tocsection {}{1}{Purpose}}{4}

?

I'm writing a research paper with latex, and Purpose is the first section (the command I'm using is \section{Purpose}). It's saying line 1 has the error, which is \documentclass{article}. Can anyone help me with this error?

---

1) Most probably "l.1" refers to the first line of the TOC file, not of the TEX file. It's impossible to tell for sure from the little snippet you've shown.

2) First thing to try in this situation will be to delete (or better to move to some temp. place) all the TeX-generated files in your working folder. Usually this means that only TEX and BIB files should remain (and any figures if you have them). Then run the usual latex; bibtex; latex; latex sequence.

3) If you still get the same error, there is probably some package conflict. To diagnose that, we'll need all of your preamble.