# PDF with equations to EPUB: the honest result

Source: https://epubcc.com/cases/equations-math-paper/ (updated 2026-11-04)

Equations are the weak point: the EpubCC engine keeps the prose and simple inline symbols, but display equations with fractions, sums and subscripts come out as scrambled plain text, because it does not build MathML yet. On the DPO paper (arXiv, CC BY 4.0) our 8-gram recall is 0.814, behind OpenDataLoader (0.860) and PDFium (0.838).

Problem: Display equations with fractions, sums, exponents and subscripts; Greek letters in running text; theorem-style derivations in the appendix.

- Limitation: Display equations are written as plain text in the order the PDF draws them: fraction bars disappear, numerators and denominators land on separate lines, and the equation number drifts («r(x, y) = β log + β log Z(x). (5) π ref (y | x)»).
- Limitation: Subscripts are written inline with a space (π ref, π θ) instead of as subscripts; some superscripts are kept (π^SFT).
- Limitation: No MathML: a reading app cannot render or read the formulas aloud.
- Limitation: OpenDataLoader (0.860), PDFium (0.838) and pdftotext (0.827) have a higher 8-gram recall than our engine (0.814); the reference skips equations, so this measures the prose.
- Limitation: The sample's title came out as «4 Direct Preference Optimization» (the first heading of the pages converted), not the paper's title.