Add demo of formatted math in Roxygen header with LaTeX

[Copilot]

This PR adds a comprehensive demonstration of LaTeX math formatting in roxygen2 documentation for R packages.

Changes Made

• New Function: Created math_demo() function in R/math_demo.R that demonstrates various LaTeX math formatting techniques in roxygen2 documentation
• Documentation Examples: The function showcases:
  • Display equations using \deqn{} (quadratic formula)
  • Inline math using \eqn{} (Greek letters, variables, expressions)
  • Mathematical notation including summation, integrals, matrix multiplication
  • Proper text fallbacks for non-LaTeX output formats
• Implementation: The function implements a working quadratic equation solver that handles real and complex roots
• Unit Tests: Added comprehensive tests in tests/testthat/test-math_demo.R covering all scenarios (two real roots, one repeated root, complex roots, error handling)
• Documentation: Generated man/math_demo.Rd with properly formatted LaTeX math expressions
• Spelling: Updated inst/WORDLIST to include "Roxygen" and "roxygen"

Testing

• ✅ All 17 unit tests pass
• ✅ Linting clean (no errors)
• ✅ R CMD check passes with 0 errors, 0 warnings, 0 notes
• ✅ Code review feedback addressed (floating-point comparison fix)
• ✅ No security vulnerabilities detected

The implementation provides a practical example for developers who want to include mathematical notation in their R package documentation using LaTeX syntax, following the tidyverse style guide and using roxygen2 with Markdown syntax.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add demo of formatted math in Roxygen header with LaTeX</issue_title>
<issue_description></issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add demo of formatted math in Roxygen header with LaTeX #16

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

[d-morrison]

@copilot try again

[Copilot]

@copilot try again

Done! I've added a comprehensive demo function showing LaTeX math formatting in Roxygen documentation. The math_demo() function demonstrates:

• Display equations with \deqn{} (quadratic formula)
• Inline math with \eqn{} (Greek letters, variables)
• Various mathematical notation (summation, integrals, matrices)
• Proper text fallbacks for non-LaTeX output

All tests pass, linting is clean, and R CMD check succeeds. Commits: 2d35334, 8c2172a

Example output:

math_demo(1, -5, 6)  # Two real roots
[1] 3 2

math_demo(1, 2, 5)   # Complex roots
[1] -1+2i -1-2i

The documentation shows proper LaTeX rendering in help files with equations like the quadratic formula, discriminant notation, and Greek letters.

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