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

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

1. Apply replacements one class at a time, not all at once. Compile after each class to verify nothing else broke.
2. For each replacement, prefer \textXX{...} over \XXshape ... \normalfont because the former auto-restores font state on }.
3. 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.
4. 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.