Analytics Archives - Page 3 of 6

Three Bugs That Would Have Stayed Hidden in Excel

When you convert an optimization model from Excel to standalone Python, you expect to do some work. You expect to rewrite the data loading, restructure the variable definitions, test the output. What you don’t expect is for the model to fail in three distinct ways, each one caused by something the Excel version was handling silently without you knowing it.

That’s what happened here. Three bugs. All real. All the kind that would have stayed invisible forever if the model had stayed in the spreadsheet.

PuLP, MILP, and CBC: The Alphabet Soup Behind Your Schedule

PuLP is a Python library for writing optimization models. MILP stands for Mixed Integer Linear Program. CBC is an open-source solver. Together, they’re what makes the Staff Scheduler work — and together, they represent something I find genuinely interesting: the fact that problems that used to require expensive commercial software and specialized hardware can now be solved on a laptop, for free, in a few seconds.

Let me explain what’s actually happening under the hood.

The Client Who Changed His Mind (And Why I Finished the Job Anyway)

Years ago, I was doing gigs on Fiverr. Mostly Excel work — macros, pivot tables, solver models. I had a profile and a handful of listings, and I’d written about that whole love/hate experience back in 2017 (short version: the clients who treat you like a vending machine are the price you pay for the ones who bring you genuinely interesting problems). One day, a genuinely interesting problem showed up.

A training company needed help scheduling their staff. Multiple clients, multiple courses, multiple instructors, limited hours, shared equipment, weird simultaneous constraints. Classic Operations Research territory. I said yes.

Continue reading “The Client Who Changed His Mind (And Why I Finished the Job Anyway)”

How many days is five months

“How many days in five months” is a very strange question to write a post about but I am learning about SEO (Search Engine Optimization). And using Ahrefs keyword research tool I found out the question is a very good keyword to target. At the end, I explain how to calculate it using Excel (or any spreadsheet).

This is what Google tells us:

Shadow price in linear programming

Linear programming is a mathematical method that is used to optimize the allocation of resources. It can be applied to a wide range of problems, such as maximizing profits or minimizing costs. One of the key concepts in linear programming is the shadow price, which can be used to determine how a change in one of the constraints of a linear programming problem affects the optimal solution.