Standardize LaTeX math notation: replace pmatrix with bmatrix across all lecture files

[Copilot]

This PR standardizes LaTeX math notation throughout the lecture files by replacing all instances of pmatrix with bmatrix to align with the QuantEcon style guide.

Changes Made

• 7 lecture files updated with consistent bmatrix notation
• 43 total replacements of \begin{pmatrix} → \begin{bmatrix} and \end{pmatrix} → \end{bmatrix}
• All LaTeX syntax remains properly balanced and valid

Files Modified

• lectures/svd_intro.md (3 instances)
• lectures/stats_examples.md (1 instance)
• lectures/lagrangian_lqdp.md (13 instances)
• lectures/multi_hyper.md (3 instances)
• lectures/opt_transport.md (7 instances)
• lectures/newton_method.md (13 instances)
• lectures/lake_model.md (3 instances)

Example Change

Before:

X = \begin{pmatrix}
    U_{t+1}/N_{t+1} \\
    E_{t+1}/N_{t+1}
\end{pmatrix}

After:

X = \begin{bmatrix}
    U_{t+1}/N_{t+1} \\
    E_{t+1}/N_{t+1}
\end{bmatrix}

The changes are purely stylistic and maintain all mathematical content while ensuring consistency with the established style guide. All matrix expressions now use square brackets (bmatrix) instead of parentheses (pmatrix).

Fixes #314.

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[mmcky]

Here is the relevant style guide page

https://manual.quantecon.org/styleguide/math.html

[github-actions]

🚀 Deployed on https://689acc9ad8b1fe2f5ee3d06e--nostalgic-wright-5fa355.netlify.app

[mmcky]

This PR updates the bracket style for matrices to use square brackets.

• this issue should be copied to other lecture repositories for the style to be unified across the lecture series.

[jstac]

Thanks @mmcky

[mmcky]

@bishmaybarik would you have time to look through the diff of this PR and cross-check to see if these changes are consistent and make sense in context? I have had a pretty good look myself and we can discuss when we link up on Thursday.

[bishmaybarik]

Hi @mmcky, I'd love to go through the PR and flag any points that is not consistent. I'll let you know by Thursday during our meeting.

[bishmaybarik]

Hey @mmcky, I have checked the changes and the PR, and I guess this looks good!

[mmcky]

@HumphreyYang this is good to merge.

The changes are just updating the style of matrices brackets (to use square brackets) but let me know if you think we should hold until 26th August 2025 re: @thomassargent30 teaching.

[mmcky]

Hey @mmcky, I have checked the changes and the PR, and I guess this looks good!

Thanks @bishmaybarik for a second set of eyes. It's a big help.

[HumphreyYang]

Many thanks @mmcky,

It looks great to me! It does not touch on the lectures we are working on now.

[mmcky]

@copilot is it possible for you to open a tracking issue in https://github.com/QuantEcon/meta that suggests this style review for other lecture series.
It would be great if you could add a checklist in the markdown of all lecture repositories in the QuantEcon organisation that start with lecture- in the repository name, and link this PR to the list item for lecture-python.myst and check it off.

[Copilot]

@copilot is it possible for you to open a tracking issue in https://github.com/QuantEcon/meta that suggests this style review for other lecture series.
It would be great if you could add a checklist...

I'm unable to create GitHub issues directly, but I can provide you with the tracking issue content that you can create manually in the QuantEcon/meta repository.

Based on my search of the QuantEcon organization, here are all the repositories starting with "lecture-":

Tracking Issue: Standardize LaTeX Matrix Notation Across Lecture Repositories

This tracks the progress of updating matrix notation from pmatrix to bmatrix across all QuantEcon lecture repositories to align with the style guide.

Progress Checklist:

• lecture-python.myst (completed in PR [link to current PR])
• lecture-source-py (archived)
• lecture-source-jl (archived)
• lecture-julia.notebooks
• lecture-python-programming.notebooks
• lecture-datascience.notebooks
• lecture-julia.myst
• lecture-python
• lecture-datascience.myst
• lecture-python-programming.myst
• lecture-python-advanced
• lecture-python-advanced.myst
• lecture-python-advanced.notebooks
• lecture-python-programming
• lecture-python-intro
• lecture-python-intro.notebooks
• lecture-jax
• lecture-econometrics-machine-learning
• lecture-intro.zh-cn
• lecture-python.notebooks
• lecture-python.zh-cn
• lecture-jax.notebooks

Reference: QuantEcon Style Guide - Math Notation

You can create this issue in the QuantEcon/meta repository and update the checklist as repositories are processed.