SwiftMath Missing Features - Implementation Status

February 3, 2026 · View on GitHub

This document lists LaTeX features that are not yet implemented in SwiftMath, based on comprehensive testing against the LaTeX Mathematics reference.

Summary

Total Features Tested: 12
Fully Implemented: 9 (75%)
Partially Implemented: 0 (0%)
Not Implemented: 3 (25%)

HIGH PRIORITY Features (Not Implemented)

1. ✅ `\displaystyle` and `\textstyle` - IMPLEMENTED

Status: ✅ Working Description: Commands to force display or text style rendering within expressions

Test Results: All tests passed

\displaystyle \sum_{i=1}^{n} x_i - ✅ Works
\textstyle \int_{0}^{\infty} f(x) dx - ✅ Works
Inline displaystyle fractions - ✅ Works

2. ❌ `\middle` - Delimiter in Middle of Expression

Status: ❌ Not Implemented Error: Invalid command \middle

Description: Used with \left and \right to add delimiters in the middle of expressions

Examples:

\left( \frac{a}{b} \middle| \frac{c}{d} \right)
\left\{ x \middle\| y \right\}

Use Case: Set notation, conditional expressions, piecewise functions with multiple sections

3. ✅ `\substack` - Multi-line Limits and Subscripts - IMPLEMENTED

Status: ✅ Working Description: Creates multi-line subscripts and limits for operators

Test Results: All tests passed

\substack{a \\ b} - ✅ Works
\sum_{\substack{0 \le i \le m \\ 0 < j < n}} P(i,j) - ✅ Works (nested in subscript)
\prod_{\substack{p \text{ prime} \\ p < 100}} p - ✅ Works (nested in subscript)
\substack{\frac{a}{b} \\ c} - ✅ Works (with nested commands)

Use Case: Complex summation/product limits, constrained expressions

Implementation: Uses buildInternal(true) pattern, handles implicit tables created by \\ within braces.

4. ✅ Manual Delimiter Sizing: `\big`, `\Big`, `\bigg`, `\Bigg` - IMPLEMENTED

Status: ✅ Working Description: Manually control delimiter sizes (4 levels beyond normal)

Test Results: All tests passed

\big( x \big) - ✅ Works (1.2x font size)
\Big[ y \Big] - ✅ Works (1.8x font size)
\bigg\{ z \bigg\} - ✅ Works (2.4x font size)
\Bigg| w \Bigg| - ✅ Works (3.0x font size)

Supported Commands:

\big, \Big, \bigg, \Bigg - basic sizing
\bigl, \Bigl, \biggl, \Biggl - left delimiter variants
\bigr, \Bigr, \biggr, \Biggr - right delimiter variants
\bigm, \Bigm, \biggm, \Biggm - middle delimiter variants

Use Case: Fine control over delimiter appearance, nested expressions

Implementation: Added delimiterHeight property to MTInner, stores size multiplier (1.2, 1.8, 2.4, 3.0), applied in MTTypesetter.makeLeftRight().

5. ❌ Spacing Commands: `\,`, `\:`, `\;`, `\!`

Status: ❌ Partially Not Implemented Error: Invalid command \: (and likely others)

Description: Fine-tuned horizontal spacing control

Command	Description	Width
`\,`	Thin space	3/18 em
`\:`	Medium space	4/18 em
`\;`	Thick space	5/18 em
`\!`	Negative thin space	-3/18 em

Examples:

a\,b                              % thin space
\int\!\!\!\int f(x,y) dx dy      % tight double integral
x \, y \: z \; w                  % mixed spacing

Use Case: Fine typography control, integral notation, custom spacing

MEDIUM PRIORITY Features

6. ✅ Multiple Integral Symbols: `\iint`, `\iiint`, `\iiiint` - IMPLEMENTED

Status: ✅ Working Description: Special symbols for double, triple, and quadruple integrals

Test Results: All tests passed

\iint f(x,y) dx dy - ✅ Works (double integral)
\iiint f(x,y,z) dx dy dz - ✅ Works (triple integral)
\iiiint f(w,x,y,z) dw dx dy dz - ✅ Works (quadruple integral)
\iint_{D} f(x,y) dA - ✅ Works (with subscript limits)

Use Case: Multivariable calculus, surface and volume integrals

Implementation: Added U+2A0C (quadruple integral) Unicode character to operator definitions.

7. ✅ `\cfrac` - Continued Fractions - IMPLEMENTED

Status: ✅ Working Description: Optimized layout for continued fractions

Test Results: All tests passed

Simple \cfrac{1}{2} - ✅ Works
Nested continued fractions - ✅ Works

7b. ✅ `\dfrac` and `\tfrac` - Display/Text Style Fractions - IMPLEMENTED

Status: ✅ Working Description: Fractions with forced display or text style

Test Results: All tests passed

\dfrac{1}{2} - ✅ Works (display-style fraction)
\tfrac{a}{b} - ✅ Works (text-style fraction)
y'=-\dfrac{2}{x^{3}} - ✅ Works (complex expression)
Nested \dfrac and \tfrac - ✅ Works

Use Case:

\dfrac forces display style (larger, more readable fractions)
\tfrac forces text style (smaller, inline fractions)
Useful when you want consistent fraction appearance regardless of context

Implementation: Prepends style atoms to numerator and denominator to force rendering style.

8. ✅ `\boldsymbol` - Bold Greek Letters - IMPLEMENTED

Status: ✅ Working Description: Creates bold Greek letters (whereas \mathbf doesn't work for Greek)

Test Results: All tests passed

\boldsymbol{\alpha} - ✅ Works (bold alpha)
\boldsymbol{\beta} - ✅ Works (bold beta)
\boldsymbol{\gamma} - ✅ Works (bold gamma)
\boldsymbol{\alpha} + \boldsymbol{\beta} = \boldsymbol{\gamma} - ✅ Works (expression)

Use Case: Vectors with Greek symbols, bold emphasis for Greek letters

Implementation: Uses bold math font for Greek and other symbols.

9. ✅ Starred Matrix Environments: `pmatrix`, `bmatrix`, etc. - IMPLEMENTED

Status: ✅ Working Description: Matrix environments with optional column alignment

Test Results: All tests passed

\begin{pmatrix*}[r] 1 & 2 \\ 3 & 4 \end{pmatrix*} - ✅ Works (right align)
\begin{bmatrix*}[l] a & b \\ c & d \end{bmatrix*} - ✅ Works (left align)
\begin{vmatrix*}[c] x & y \\ z & w \end{vmatrix*} - ✅ Works (center align)
\begin{matrix*}[r] 10 & 20 \\ 30 & 40 \end{matrix*} - ✅ Works (no delimiters)

Alignment Options: [r] = right, [l] = left, [c] = center

Use Case: Financial tables, aligned numerical data in matrices

Implementation: Added readOptionalAlignment() function, modified readString() to accept asterisks, applies alignment to all columns.

10. ✅ `\smallmatrix` Environment - IMPLEMENTED

Status: ✅ Working Description: Compact matrix for inline use (smaller than regular matrices)

Test Results: All tests passed

\left( \begin{smallmatrix} a & b \\ c & d \end{smallmatrix} \right) - ✅ Works (with delimiters)
A = \left( \begin{smallmatrix} 1 & 0 \\ 0 & 1 \end{smallmatrix} \right) - ✅ Works (identity matrix)
\begin{smallmatrix} x \\ y \end{smallmatrix} - ✅ Works (column vector)

Use Case: Inline matrices, transformation matrices in text, compact notation

Implementation: Uses .script style for smaller font size, tighter column spacing (6 vs 18), no built-in delimiters.

Implementation Priority Recommendations

Remaining High Priority Features

Spacing commands (\,, \:, \;, \!) - Used in almost all advanced math
\middle - Useful for conditional notation

Testing Coverage

All tests use the MTMathListBuilder.build(fromString:error:) API and automatically skip with XCTSkip when features are not implemented.

Test File: Tests/SwiftMathTests/MTMathListBuilderTests.swift Test Functions:

testDisplayStyle() - ✅ Passed (IMPLEMENTED)
testMiddleDelimiter() - ⏭️ Skipped (not implemented)
testSubstack() - ✅ Passed (IMPLEMENTED)
testManualDelimiterSizing() - ✅ Passed (IMPLEMENTED)
testSpacingCommands() - ⏭️ Skipped (not implemented)
testMultipleIntegrals() - ✅ Passed (IMPLEMENTED)
testContinuedFractions() - ✅ Passed (IMPLEMENTED)
testBoldsymbol() - ✅ Passed (IMPLEMENTED)
testStarredMatrices() - ✅ Passed (IMPLEMENTED)
testSmallMatrix() - ✅ Passed (IMPLEMENTED)

Notes for Future Implementation

For `\middle`:

Needs integration with existing \left...\right delimiter pairing system
Should support all delimiter types that work with \left and \right

For Spacing Commands:

Need to insert proper MTMathSpace atoms
Different space types: positive (\,, \:, \;) and negative (\!)
Some might already be partially implemented

Generated: 2025-10-01 SwiftMath Version: Based on iosMath v0.9.5 Last Updated: 2026-01-11 - Updated \boldsymbol as implemented; added example images Last Updated: 2026-01-07 - All features from October 2025 remain current. Recent work has focused on line breaking improvements and tokenization infrastructure.