Largest Mersenne Prime number

Sometimes I like to doodle and I often like to doodle with code.

Coding an isPrime function is a popular software engineering interview question. I’ve been on many hiring committees over the years and I’ve asked for code to determine if a number was prime many times. In a whiteboard interview, it’s common to ask for some code and then when the interviewee supplies something that works, ask them to make it more efficient. While asking for a function to determine if a number is prime is mathematical and I’m generally not hiring a mathematician, the concept of primes is…


Printer working an early Gutenberg letterpress from the 15th century.

This article provides instruction on using tools and a process that will help create and share content online. Some of these tools are used by Web Developers and the instructions will be familiar. I have provided links and instructions for less experienced readers and hope that these tools can be learned along with learning how to produce a book online.

Teaching Online

As an online Web Development instructor, I look for ways to share content online. There are a lot of tools in the online instructor’s toolbox that help with sharing content. Canvas is where assignments are shared and grades…


I was at a meetup where a fellow attendee described to me a layout question that he got in an interview. He drew the a picture of the information given in the interview and was told that it required absolute positioning and would need to be responsive. I have my favorite layout techniques, but this made me realize that there are in fact many way to achieve side by side layout.

The evolution of web page layout tracks the evolution of the CSS and HTML Specifications and Standards. …


If you’re learning R you’ve come across the sort, rank and order functions. Because there is similarity and even overlap in the semantics, questions come up: what exactly does each do and what are the use cases for each?

All three functions require that the values they operate on are comparable. Comparisons in R can apply to string, numeric, complex and logical date types.

Rank vs Order Confusion

Sort, Rank, and Order are functions in R. They can be applied to a vector or a factor. If you are used to thinking of data in terms of rows and columns, vector represents a column…


Map-List: JavaScript Data Structure That Models Applications

Front end developers create data driven web sites. Whether we render forms or data visualizations, we are trying to communicate and maintain the state of our data using visuals. It make sense to develop an underlying structure which parallels the rendering and interaction with that data. Map-List is a structure which does that. While it’s common to develop such structures in a language like Java, JavaScript applications tend to use the array functions. …

Rebecca Peltz

Software/Web Engineer and Instructor

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