Modernize

modernize — port deprecated LaTeX to LaTeX2e

Most of these patterns still compile but produce subtle bugs (broken NFSS interactions, wrong math spacing, miscalibrated boxes). Replace conservatively.

The replacement table

Deprecated	Modern	Why
{\bf foo}	\textbf{foo}	\bf is a switch that resets shape; \textbf is NFSS-aware
{\it foo}	\textit{foo}	same
{\sl foo}	\textsl{foo}	same
{\sc foo}	\textsc{foo}	same
{\rm foo}	\textrm{foo}	same
{\sf foo}	\textsf{foo}	same
{\tt foo}	\texttt{foo}	same
\bf (declaration form)	\bfseries	NFSS declaration; stacks correctly
\it (declaration form)	\itshape	same
\sl (declaration form)	\slshape	same
\sc (declaration form)	\scshape	same
\rm (declaration form)	\rmfamily	same
\sf (declaration form)	\sffamily	same
\tt (declaration form)	\ttfamily	same
\bf\it foo (combined)	\textbf{\textit{foo}}	\bf resets shape; combining old commands silently fails
\centerline{X}	\begin{center}X\end{center} (or {\centering X\par})	\centerline is plain TeX, doesn't interact with \par
\begin{eqnarray}...\end{eqnarray}	\begin{align}...\end{align} (from amsmath)	eqnarray miscalibrates math-relation column spacing; flagged obsolete
\begin{eqnarray*}...\end{eqnarray*}	\begin{align*}...\end{align*}	same
$$...$$	\[...\] (or equation/align)	plain TeX $$ skips \everydisplay, breaks amsmath features
\over (math)	\frac{a}{b}	\over is plain TeX, no semantic info
{a \over b}	\frac{a}{b}	same
\usepackage{epsfig}	\usepackage{graphicx}	epsfig is a thin wrapper for the deprecated graphics package
\epsfig{file=X,...}	\includegraphics[...]{X}	same
\usepackage[latin1]{inputenc}	drop (or switch source to UTF-8)	LaTeX 2018+ defaults to UTF-8
\usepackage[utf8]{inputenc} (LuaLaTeX/XeLaTeX)	drop entirely	both engines are natively Unicode
\usepackage[T1]{fontenc} (LuaLaTeX/XeLaTeX)	drop entirely; use fontspec	T1 is for pdflatex's 8-bit font world
\rm inside math	\mathrm{...} (text in math) or \operatorname{...} (operator name)	\rm in math is undefined behavior in modern LaTeX
\fbox{\parbox{...}{...}} callouts	\fbox{\parbox{...}{...}} works, but for tunable callouts use tcolorbox	wider styling control

Sources: TeX FAQ (https://texfaq.org/FAQ-2letterfontcmd); LaTeX2e for class/package writers (https://www.latex-project.org/help/documentation/usrguide.pdf); latexref.xyz/eqnarray.html.

Procedure

1. Read the document before any rewriting. Confirm engine target (pdflatex / xelatex / lualatex) — some replacements differ.
2. Search for legacy patterns:

   grep -nE '\\(bf|it|sl|sc|rm|sf|tt)\b' main.tex
   grep -nE '\\begin\{eqnarray\*?\}' main.tex
   grep -nE '\\\$\\\$|\$\$.*\$\$' main.tex     # naive — false positives possible
   grep -nE '\\centerline\b' main.tex
   grep -nE '\\epsfig\b|\\usepackage\{epsfig\}' main.tex
   grep -nE '\\usepackage(\[[^\]]*\])?\{inputenc\}' main.tex
   grep -nE '\\over\b' main.tex
   

3. Apply replacements one class at a time, not all at once. Compile after each class to verify nothing else broke.
4. For each replacement, prefer \textXX{...} over \XXshape ... \normalfont because the former auto-restores font state on }.
5. For eqnarray → align: also rewrite the &=& columns to &= (eqnarray has 3 columns, align has 2). Add \usepackage{amsmath} to preamble if absent. Preserve \nonumber and equation labels.
6. For inputenc/fontenc on modern engines: drop both lines; recompile under xelatex/lualatex with fontspec.

eqnarray → align — concrete rewrite

Before:

\begin{eqnarray}
  a &=& b + c \\
  &=& d \nonumber
\end{eqnarray}

After:

\begin{align}
  a &= b + c \\
  &= d \nonumber
\end{align}

Source: amsldoc PDF (amsmath documentation), §3.

Brace-balanced {\bf ...} rewriting

A naive regex rewrite of {\\bf (.+?)} is incorrect — nested braces aren't matched. Algorithm:

1. Locate {\bf (or other declaration). The { opened the group.
2. Walk forward, tracking brace depth. The matching } closes the group.
3. Replace {\bf X} with \textbf{X}.
4. If the group contains multiple paragraphs (\par or blank line), use the declaration form {\bfseries X} instead — \textbf doesn't allow paragraphs.

If the document is large and a script is wanted, write a small Python preprocessor (call from scripts/):

# scripts/modernize_font_switches.py — illustrative
import re, sys
SHORT_TO_LONG = {'bf':'textbf','it':'textit','sl':'textsl','sc':'textsc',
                 'rm':'textrm','sf':'textsf','tt':'texttt'}
# Match {\bf ...} or {\it ...} balanced. Use the `regex` package (pip install regex)
# for recursive-pattern matching, or write a small stateful walker.

(Don't run such a script on a paper without diffing the output. False positives in math mode or comments are common.)

Verifying after modernization

1. Recompile. Errors decrease, ideally to zero.
2. Compare PDFs visually — /academic-latex:verify-visual with the original as reference. Spacing should be the same or slightly better; substantive layout shifts indicate an over-aggressive rewrite.
3. Check math regions especially carefully. eqnarray has known wrong spacing, so a small spacing change in equations is expected and good.

When NOT to modernize

• The document compiles cleanly and the user is just patching one bug. Don't expand scope.
• A journal class explicitly uses a deprecated pattern internally — don't rewrite the class.
• The deprecated commands are inside verbatim/listings environments (they're code samples).

When uncertain

For mappings not in the table above (e.g., obscure plain-TeX primitives, custom legacy macros, or deprecated package options), delegate to /academic-latex:docs-lookup. Cite the exact source for any non-trivial mapping you propose.

Last verified

2026-05-09 — TeX FAQ, LaTeX2e usrguide, latexref.xyz, amsldoc.