ERROR: problems during latex INPUT: \documentclass[fleqn,12pt]{article} \usepackage{amsmath} \usepackage[normal]{xcolor} \setlength{\mathindent}{0cm} \definecolor{teal}{rgb}{0,0.5,0.5} \definecolor{navy}{rgb}{0,0,0.5} \definecolor{aqua}{rgb}{0,1,1} \definecolor{lime}{rgb}{0,1,0} \definecolor{maroon}{rgb}{0.5,0,0} \definecolor{silver}{gray}{0.75} \usepackage{latexsym} \begin{document} \pagestyle{empty} \pagecolor{white} { \color{black} \begin{math}\displaystyle D + D \rightarrow \cases{^3He + n \cr \quad T + p\end{math} } \clearpage { \color{black} \begin{math}\displaystyle \frac{n_n}{n_p} = \cases{(\frac{m_n}{m_p})^{\frac{3}{2}} = 1 \qquad ;\ E_K \gg 1MeV \cr 0 \qquad \qquad \qquad ;\ E_K \rightarrow O\end{math} } \clearpage { \color{black} \begin{math}\displaystyle n + \ ^3He \rightarrow \cases{\quad T + p \cr ^4He + \gamma\end{math} } \clearpage \end{document} STDERR: This is pdfTeX, Version 3.141592653-2.6-1.40.24 (TeX Live 2022/Debian) (preloaded format=latex) restricted \write18 enabled. entering extended mode (/tmp/8JMkoB3IPJ/yYnlFklrfu LaTeX2e <2022-11-01> patch level 1 L3 programming layer <2023-01-16> (/usr/share/texlive/texmf-dist/tex/latex/base/article.cls Document Class: article 2022/07/02 v1.4n Standard LaTeX document class (/usr/share/texlive/texmf-dist/tex/latex/base/fleqn.clo) (/usr/share/texlive/texmf-dist/tex/latex/base/size12.clo)) (/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsmath.sty For additional information on amsmath, use the `?' option. (/usr/share/texlive/texmf-dist/tex/latex/amsmath/amstext.sty (/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsgen.sty)) (/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsbsy.sty) (/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsopn.sty)) (/usr/share/texlive/texmf-dist/tex/latex/xcolor/xcolor.sty (/usr/share/texlive/texmf-dist/tex/latex/graphics-cfg/color.cfg) (/usr/share/texlive/texmf-dist/tex/latex/graphics-def/dvips.def) (/usr/share/texlive/texmf-dist/tex/latex/graphics/mathcolor.ltx)) (/usr/share/texlive/texmf-dist/tex/latex/base/latexsym.sty) (/usr/share/texlive/texmf-dist/tex/latex/l3backend/l3backend-dvips.def) No file yYnlFklrfu.aux. (/usr/share/texlive/texmf-dist/tex/latex/base/ulasy.fd) ! Package amsmath Error: Old form `\cases' should be \begin{cases}. See the amsmath package documentation for explanation. Type Hfor immediate help. ... l.17 ...ath}\displaystyle D + D \rightarrow \cases {^3He + n \cr \quad T + p\... ! Misplaced \cr. l.17 ...tyle D + D \rightarrow \cases{^3He + n \cr \quad T + p\end{math} ! Missing } inserted. } l.17 ... \cases{^3He + n \cr \quad T + p\end{math} [1] ! Package amsmath Error: Old form `\cases' should be \begin{cases}. See the amsmath package documentation for explanation. Type H for immediate help. ... l.22 ...ath}\displaystyle \frac{n_n}{n_p} = \cases {(\frac{m_n}{m_p})^{\frac{... ! Misplaced \cr. l.22 ...frac{3}{2}} = 1 \qquad ;\ E_K \gg 1MeV \cr 0 \qquad \qquad \qquad ;\... ! Missing } inserted. } l.22 ...quad \qquad ;\ E_K \rightarrow O\end{math} [2] ! Package amsmath Error: Old form `\cases' should be \begin{cases}. See the amsmath package documentation for explanation. Type H for immediate help. ... l.27 ...displaystyle n + \ ^3He \rightarrow \cases {\quad T + p \cr ^4He + \g... ! Misplaced \cr. l.27 ... \ ^3He \rightarrow \cases{\quad T + p \cr ^4He + \gamma\end{math} ! Missing } inserted. } l.27 ...es{\quad T + p \cr ^4He + \gamma\end{math} [3] (./yYnlFklrfu.aux) ) (see the transcript file for additional information) Output written on yYnlFklrfu.dvi (3 pages, 1448 bytes). Transcript written on yYnlFklrfu.log.