Oscar Merida

twitter: @omerida


PHP Puzzles: Compounding Interest

By Oscar Merida

Last month, we looked at how to output an amortization table to see how compounding interest affects some amount of money. Printing out such a table assumes we have a certain set of inputs. Moreover, it’s tedious, even simple for a computer to do. Let’s look at other ways to calculate the time value of money. by Oscar Merida

Published in The Art of Data, November 2021 —Available for Free

PHP Puzzles: Time Value of Money

By Oscar Merida

Is it better to get $100 today or $110 in one years time? The answer’s not straightforward because you could use $100 today to potentially earn more than $10 over 12 months. How do you know what to do? For that, you need to know how to calculate a rate of return or use it to compare amounts of money at different times. Hold on for a bit, we’re bending the time—space (money?) continuum.

Published in Decrypting Cryptography, October 2021

PHP Puzzles: Sending and Receiving Polybius Ciphers

By Oscar Merida

Ciphers come in many different forms and have been used since ancient times to encode and decode vital messages. Today, we use complicated mathematics to encrypt and decrypt messages. Typically, we depend on shared and secret keys to ensure the message is only readable by the intended recipients. What if you don’t have the computing power of a modern device at your disposal? This month, let’s look at using Polybius Squares to share secret messages.

Published in Testing Assumptions, May 2021

Streamlining Behat

By Oscar Merida

Behat, and feature tests overall, are crucial for giving you confidence that when you refactor code, you don’t change how an application works and for helping you understand how an application behaves in practice. Investing in integration and functional tests is worth it in the long term, and in this article, we’ll see how I also updated my Behat setup to run browser tests in Chrome.

Published in Testing Assumptions, May 2021 —Available for Free