I am using LaTeX for first time. However, I am writing a report based on someone else's. I have noticed that TeXStudio does not recognise:

\thesection
\thesubsection
\topmargin


They appear to be highlighted in orange and a small reading saying "Unrecognized command" appears when the cursor is placed over them. Hence, I am pretty much limited to do not modify the format of my heads and foots when using fancyhdr.

The following is one part of the document:

\documentclass[a4paper,12pt]{report}
\usepackage[utf8]{inputenc}

\usepackage[english]{babel}
\usepackage{amsmath,amsthm}
\usepackage{amsfonts}
\usepackage{graphicx}
\usepackage{float}
\usepackage{fullpage}
\usepackage{fancyhdr}
\usepackage{booktabs}
\usepackage{parskip}
\usepackage[font=small, labelfont=bf]{caption}

\renewcommand*\thesection{\arabic{section}.0}
\renewcommand*\thesubsection{\arabic{section}.\arabic{subsection}}

\pagestyle{fancyplain}
\setlength{\topmargin}{0pt}

\begin{document}
\input{./titlepage.tex}

\lfoot{Whatever I want as the foot}
\rfoot{\thepage}
\cfoot{}


This, however, produces well numbered sections and subsections (1.0, 2.0, 3.0, 3.1, 3.2, etc) and the right head as the title of the section.

The problem is that I cannot change the the length of the head and foots, as any value inserted in \headheight does not produce any change at all.

Any idea about what am I doing wrong?

-

## closed as too localized by egreg, lockstep, Joseph Wright♦Apr 6 '13 at 21:19

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Welcome to TeX.sx! Usually, we don't put a greeting or a "thank you" in our posts. While this might seem strange at first, it is not a sign of lack of politeness, but rather part of our trying to keep everything very concise. Upvoting is the preferred way here to say "thank you" to users who helped you. A tip: If you indent lines by 4 spaces or enclose words in backticks , they'll be marked as code, as can be seen in my edit. – egreg Sep 19 '12 at 9:33
BTW: why did you delete the changes of @egreg? The backticks helps to recognise inline code easier and a  is missing in front of you documentclass. Please reread the comment of egreg. – Kurt Sep 19 '12 at 13:43
Usually, we don't put a greeting or a "thank you" in our posts. While this might seem strange at first, it is not a sign of lack of politeness, but rather part of our trying to keep everything very concise. Upvoting is the preferred way here to say "thank you" to users who helped you. – egreg Sep 19 '12 at 13:46
TeXStudio doesn't know about all legal commands; the \headheight` should be at least 14.5pt as a message in the log file tells you. – egreg Sep 19 '12 at 14:08
I deleted what @egreg edited because I did not know how these threads work. Now I do. So the heads cannot be smaller than 14.5pt at all? Is there any other command/code to edit the heads (font, size, etc)? – Alejo Sep 27 '12 at 11:26