base/eqalign-to-aligned-env - TeXForm rewrite rule

Level: AuthoringFaithfulCorpusEquivEvery profile applies this rule; its output remains suitable for authoring.
Fidelity: readingPreserves notation, reading order, and structural roles.
Package: base
Source: base/authoring/plain_tex_matrix/eqalign_to_aligned_env.rs (opens in new tab)
Triggers: \eqalign command
Eliminates: \eqalign command
Produces: aligned environment
Touches: \cr, \\, \newline commands

Rewrite patterns#

cr\eqalign{#1 \cr #2}\begin{aligned} #1 \\ #2 \end{aligned}
linebreak-arguments\eqalign{#1 \\*[#2] #3}\begin{aligned} #1 \\*[#2] #3 \end{aligned}
newline\eqalign{#1 \newline #2}\begin{aligned} #1 \\ #2 \end{aligned}
leading-row-scripts\eqalign{#1 \cr_{#2}^{#3}#4}\begin{aligned} #1 \\{}_{#2}^{#3}#4 \end{aligned}
leading-row-primes\eqalign{#1 \cr'#2}\begin{aligned} #1 \\{}'#2 \end{aligned}

Examples#

Each example shows this rule applied in isolation. A complete normalization profile may make additional changes.

Three line aligned derivatives#

Before

\eqalign{f(x)&=x^3-1 \cr f'(x)&=3x^2 \cr f''(x)&=6x}

After this rule

\begin{aligned} f(x)&=x^3-1 \\ f'(x)&=3x^2 \\ f''(x)&=6x \end{aligned}

The rendered result has pixel differences from the input.

Continued alignment#

Before

\eqalign{a&=b+c \cr &=d}

After this rule

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

The rendered result has pixel differences from the input.

Same family#

ams/Bmatrix-env-to-brace-matrix Rewrite the fenced Bmatrix environment to explicit braces around a core matrix environment.
ams/Vmatrix-env-to-Vert-matrix Rewrite the fenced Vmatrix environment to explicit double bars around a core matrix environment.
ams/bmatrix-env-to-bracket-matrix Rewrite the fenced bmatrix environment to explicit brackets around a core matrix environment.
ams/pmatrix-env-to-paren-matrix Rewrite the fenced pmatrix environment to explicit parens around a core matrix environment.
ams/vmatrix-env-to-vert-matrix Rewrite the fenced vmatrix environment to explicit vertical bars around a core matrix environment.
base/cases-to-cases-env Rewrite plain-TeX cases to the standard cases environment with row breaks.
base/eqalignno-to-align-env Rewrite eqalignno to the standard align* environment.
base/matrix-to-matrix-env Rewrite plain-TeX matrix to the standard matrix environment with row breaks.
base/pmatrix-to-pmatrix-env Rewrite plain-TeX pmatrix to the standard pmatrix environment with row breaks.
physics/antidiagonalmatrix-to-admat Collapse antidiagonalmatrix to the shorter admat helper.
physics/diagonalmatrix-to-dmat Collapse diagonalmatrix to the shorter dmat helper.
physics/matrixdeterminant-to-mdet Collapse matrixdeterminant to the shorter mdet determinant helper.
physics/bmqty-to-mqty Expand bmqty to the core mqty builder with bracket fence syntax.
physics/mdet-to-vmqty Expand mdet to the vmqty determinant-style builder.
physics/pmqty-to-mqty Expand pmqty to the core mqty builder with paren fence syntax.
physics/zmat-to-xmat Expand zmat to the explicit xmat zero-filled builder.

Notes#

Convert only known body-level \cr, \\, and \newline row separators. Normalize \cr and \newline to an unstarred linebreak with no spacing argument; preserve the original star and optional spacing slots on \\ (including \\*, \\[2pt], and \\*[2pt]). Split a separator through any Scripted base chain, transfer its leading subscript, superscript, and Prime content to a fresh empty base at the start of the next row, and preserve nested script layers. Do not split separators inside explicit groups or nested environments, and leave unknown names such as \crcr untouched. Preserve real internal empty rows and the body sequence, including trailing separators. Only the plain-TeX source command is eliminated; existing AMS environments are out of scope.

Disable this rule#

TransformEngine(profile="corpus", disable_rules=["base/eqalign-to-aligned-env"])

new TransformEngine({ profile: 'corpus', disableRules: ['base/eqalign-to-aligned-env'] })

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