Forem: Mpia

LaTeX: Writing Scientific Documents Like a Pro

Mpia — Wed, 31 Dec 2025 20:08:31 +0000

After my Word document crashed for the third time, corrupting my math formulas and randomly changing my formatting... I discovered LaTeX.

And I'll never go back.

The Word nightmare we've all lived

You know the drill:

Equations that look like pixelated garbage
Formatting that breaks between saves
Copy-paste that destroys your entire layout
"Table of contents updated" [entire document shifts by 3 pages]

Sound familiar? 😅

What if your documents compiled like code?

That's exactly what LaTeX does. You write markup, compile it, get a beautiful PDF.

Why switch to LaTeX?

✅ Math formulas that actually look professional
✅ No more formatting fights - focus on content
✅ Git-friendly - version control for documents
✅ Publication-ready typography
✅ Automatic table of contents, references, numbering

Quick example

\documentclass[a4paper,11pt]{article}

\usepackage[utf8]{inputenc}
\usepackage{amsmath}

\title{My First LaTeX Document}
\author{Your Name}

\begin{document}
\maketitle

\section{Introduction}
Einstein's famous formula: $E = mc^2$

\[
    x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
\]

\end{document}

Compile → Beautiful PDF. Every single time.

What my complete guide covers

I wrote everything I wish I knew when starting:

🚀 Setup guide (VS Code, TeXstudio, Overleaf)
📝 Document structure and essential packages
🧮 Mathematical formulas (the LaTeX superpower)
💻 Source code with syntax highlighting
📊 Tables and figures done right
🎨 Colored boxes for terminal outputs
📦 Complete templates ready to use
⚙️ pdflatex vs lualatex explained

Real-world examples from the guide

Beautiful math:

\begin{align}
    \sum_{i=1}^{n} x_i &= x_1 + x_2 + \cdots + x_n \\
    \int_0^{\infty} e^{-x} dx &= 1
\end{align}

Code with highlighting:

\begin{lstlisting}[language=Python]
def fibonacci(n):
    if n <= 1:
        return n
    return fibonacci(n-1) + fibonacci(n-2)
\end{lstlisting}

Professional tables:

\begin{tabular}{|l|c|c|}
    \hline
    \textbf{Feature} & \textbf{Word} & \textbf{LaTeX} \\
    \hline
    Equations & 😭 & 🚀 \\
    \hline
    Git & ❌ & ✅ \\
    \hline
\end{tabular}

The turning point

LaTeX has a learning curve. Your first compilation error will be frustrating.

But once you get past that? You'll wonder how you ever survived with Word for technical documents.

Read the full guide here: codewithmpia.com/...

Perfect for:

🎓 CS/Math/Physics students
📚 Researchers and academics
📄 Anyone writing technical documentation
🔬 Scientists tired of equation editors

Your experience?

Already using LaTeX? Share your best tips!
Still on Word? What's holding you back?

Drop a comment below! 👇

Regular Expressions in Python: The Complete Guide to Finally Understanding Regex

Mpia — Wed, 31 Dec 2025 19:57:26 +0000

Let's be honest: you've copy-pasted a regex from Stack Overflow without really understanding what it does, right? 😅

^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$

Does this make sense to you? No? Me neither at first.

The regex problem

We all have this love-hate relationship with regular expressions:

We know they're powerful
We need them regularly
But we avoid truly understanding them

Result? We spend 30 minutes searching for the right pattern on Google instead of writing it in 2 minutes.

What if you could finally master regex?

I wrote a complete guide that demystifies regex once and for all:

✅ Basic syntax explained simply
✅ Python's re module in detail
✅ Practical examples (emails, phone numbers, URLs, passwords...)
✅ Common pitfalls to avoid
✅ Best practices for readable regex

Quick examples from the guide

Validate an email:

import re

def validate_email(email):
    pattern = r"^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$"
    return bool(re.match(pattern, email))

Extract all URLs from text:

def extract_urls(text):
    pattern = r"https?://[^\s<>\"']+"
    return re.findall(pattern, text)

Clean text intelligently:

def clean_text(text):
    text = re.sub(r"\s+", " ", text)  # Multiple spaces → single space
    text = re.sub(r"[^\w\s.,!?-]", "", text)  # Remove special chars
    return text.strip()

Stop struggling with regex

Whether you're a beginner who avoids regex or a developer tired of copy-pasting without understanding, this guide is for you.

Read the full article here: codewithmpia.com/...

No more cryptic patterns. No more trial and error. Just clear explanations and practical examples you can use today.

What's your biggest regex challenge? Share in the comments! 👇

Flask + SELinux: Fixing the Mysterious 502 Error on Alma Linux

Mpia — Fri, 28 Nov 2025 23:04:06 +0000

You deploy your Flask app on Alma Linux, everything looks perfect, you hit your URL and... BAM! 502 Bad Gateway.

You check configs, permissions, logs. Nothing works. Then you try sudo setenforce 0 and... it works! 🎉

But now you're stuck running with SELinux disabled, and you know that's not the solution.

Sound familiar? Let me show you how to fix this properly.

The Real Problem

SELinux isn't your enemy - it's just doing its job. By default, it blocks:

nginx connecting to your Gunicorn Unix socket
systemd launching Gunicorn from /home
Your app sending emails via SMTP

Basically, everything a modern web app needs to do. 😤

Quick Diagnosis

# See what SELinux is blocking
sudo ausearch -m avc -ts recent

# Check your service logs
sudo journalctl -u your-service -n 50 --no-pager

If you see Permission denied with code 203/EXEC, that's SELinux blocking you.

The Solution (Step by Step)

1. Move to `/var/www` (seriously, do it)

SELinux hates /home for web apps. Move to the standard location:

sudo systemctl stop your-service
sudo mkdir -p /var/www
sudo mv /home/user/my-app /var/www/my-app
sudo chown -R user:user /var/www/my-app
sudo restorecon -Rv /var/www/my-app  # SELinux magic!

2. Update systemd service

Edit /etc/systemd/system/your-service.service:

[Unit]
Description=Gunicorn for Flask app
After=network.target

[Service]
User=your-user
Group=your-group
WorkingDirectory=/var/www/my-app

ExecStartPre=/usr/bin/mkdir -p /var/run/my-app
ExecStartPre=/usr/bin/chown your-user:nginx /var/run/my-app
ExecStartPre=/usr/bin/chmod 755 /var/run/my-app

Environment="PATH=/var/www/my-app/venv/bin"

ExecStart=/var/www/my-app/venv/bin/gunicorn \
    --workers 4 \
    --bind unix:/var/run/my-app/my-app.sock \
    --umask 007 \
    wsgi:app

Restart=always

[Install]
WantedBy=multi-user.target

sudo systemctl daemon-reload

3. Configure SELinux contexts

# Tell SELinux the socket is legitimate
sudo semanage fcontext -a -t httpd_var_run_t "/var/run/my-app(/.*)?"
sudo restorecon -Rv /var/run/my-app

# Allow nginx to connect
sudo setsebool -P httpd_can_network_connect 1

4. Create a custom SELinux policy (THE game changer!)

This is the crucial step:

# Temporary permissive mode
sudo setenforce 0

# Start your app to generate violations
sudo systemctl restart your-service
sleep 5
curl http://localhost

# Generate custom policy from violations
sudo ausearch -m avc -ts recent | audit2allow -M my_policy

# Install the policy
sudo semodule -i my_policy.pp

# Back to enforcing mode
sudo setenforce 1

# Restart and verify
sudo systemctl restart your-service

What just happened? audit2allow analyzed all SELinux denials and created a policy that allows them. SELinux just learned what your app needs!

5. Configure nginx

upstream app_server {
    server unix:/var/run/my-app/my-app.sock fail_timeout=0;
}

server {
    listen 80;
    server_name my-domain.com;

    location / {
        proxy_pass http://app_server;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
}

sudo nginx -t
sudo systemctl reload nginx

Common Issues & Quick Fixes

Emails not sending?

sudo setsebool -P httpd_can_sendmail 1

External database connection blocked?

sudo setsebool -P httpd_can_network_connect_db 1

API calls failing?

sudo setsebool -P httpd_can_network_connect 1

Verify It Works

# Check SELinux mode (should show "Enforcing")
getenforce

# Service status
sudo systemctl status your-service

# No more violations?
sudo ausearch -m avc -ts recent

# Test your site
curl -I http://your-domain.com

If everything's green, congratulations! 🎉 You've tamed SELinux!

Golden Rules

NEVER disable SELinux in production - create policies instead
Always use /var/www for web apps
Save your .te files - you'll need them later
Use restorecon after moving files - saves hours of debugging

Want the Full Guide?

This is just the quick version! For a complete, detailed walkthrough with troubleshooting tips, deployment automation scripts, and more real-world scenarios, check out the full article on my blog:

👉 Read the complete guide on codewithmpia.com

You'll learn:

How to debug SELinux violations like a pro
Setting up automated deployment scripts
Handling edge cases and specific scenarios
Best practices for production deployments

Have you struggled with SELinux? Share your experience in the comments below!

And if this helped you fix that annoying 502 error, don't forget to share it with others who might be stuck in the same situation. 😉

May the SELinux be with you! 🐧✨

👋 About Me

Hi! I'm Mpia M., a computer science student passionate about web development. I created codewithmpia.com to share coding tutorials and make programming knowledge accessible to everyone.

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Topics I cover: Python, Django, Flask, SvelteKit, Vue.js, and DevOps.