Linear algebra tutorial in four pages

I just pushed an update to the Linear algebra explained in four pages tutorial.

Linear algebra tutorial in four pages thumbnail

Anyone who has an exam with lots of $A\vec{x}=\vec{b}$ stuff on it coming up should check it out because it covers: vector operations, matrix operations, linear transformations(matrix-vector product, fundamental vector spaces, matrix representation), solving systems of linear equations (the RREF stuff), matrix inverse, eigenvalues.

UPDATE: I found another excellent tutorial which I think you should also read, especially if you are a visual person. A Geometric Review of Linear Algebra by Prof. Eero P. Simoncelli  (discuss on HN if you are a procrastinating person). If you’re a studious person, you’ll also go to and practice solving problems. To become a powerful person, don’t look at the solution until you’ve attempted the problem (with pen and paper) for at least five minutes.

UPDATE: I found some other useful short tutorials, like this short review of linear algebra from Stanford and another one from Boulder which both cover interesting details and bring a new perspective.

One day of advertising on facebook

Early this morning, my facebook advertisement campaign of the wall post containing the word “bullshit” was approved and went live.  A total of 8684  people were shown the post in their news feed thanks to this “Page Post Engagement” campaign.

Metrics: The measurable results of 8.6k impressions are 44 Website Clicks (mostly the link to gumroad), 33 Post Likes, and 23 Page Likes. Over at the analytics panel at gumroad I see 7 visits from and 23 visits from

Conversions:  Perhaps most importantly, none of these visits converted to any sales. 🙁   Though to be realistic, perhaps I’m expecting some of these visits to convert tomorrow or after tomorrow. I’m imagining the visitors downloaded the preview PDF and will check it tonight and tomorrow and those that like what they see will come back to purchase.

I’m thinking now the ad copy wasn’t the best. Perhaps students who read the post are not ready to be sold to yet and I’m sending them to gumroad too soon… I should probably make a proper landing page with the “get this book, read it, ace the finals” pitch front and center.

I was very optimistic about this campaign because I chose my target audience to be “college students graduating in 2017” which means they are in first year right now, which is exactly my target audience.

Costs analysis  The total cost of this campaign for today was $25. I would have to make 1.25 sales/day to break even with this approach, which, with some ad copy tweaking, should be possible. At least I got lots of likes on my page now. I still can’t get over how funny (or sad?) it is that I’m paying to be liked. Here is modernity for you: you pay to be liked.

The not-so-successful launch of v4.0

I recently announced the launch of the fourth edition of the book on hacker news. This re-launch was significantly less successful than the initial launch from January 1st. I’m a little disappointed from the whole experience, but I think there are lessons to be learned here.

Was it bad timing?  I worked until late the previous night to update the website copy, but I left some things for this morning, which meant I was only able to post at 11:30AM. The “best practices” suggest 9AM–11AM EST, so I was a little out of that range.

Should-I have chosen a better title? I went with the “No bullshit guide to math and physics, v4.0” since this is basically what I was announcing. Should I have mentioned the 34% off deal on the eBook?

The interesting take away for me is that, while extremely useful, hacker news cannot be my main channel for promoting the book. I need to come-up with a repeatable and scalable strategy for attracting members of my three target audiences to the webpage. I’m now playing with google AdWords and Facebook advertisements. Let’s see if spending some money will lead to a good return on investment.

I also posted the /launch40 URL to several channels on reddit where it was very poorly received. The redditors protested the advertisement-like nature of the post. I see their point. Though, honestly, I think my book could be genuinely useful to the students at McGill and UofT. Exam season is coming after all, and I know some students could use some help! The next time I post to HN/reddit, I post the updated mechanics tutorial: useful, educational, and fun, but ending in a little advert for the book.

Linear algebra flyer

This evening I finally figured out a plan of attack for developing the Linear Algebra title.

  1. I will prepare a flyer which covers all the material.
  2. Distribute the flyer T & R 08:35AM-10:55AM MDHAR G-10 to the 88 registered in the class.
  3. The flyer will say “free eBook” and link to
  4. On the side I will ask them to sign up to the LA mailing list and then send them a free PDF of the ebook.
  5. Ask for feedback by email after the final is done

I already have setup a an LA help desk, so I will advertise that too.

Okay, better get on this ASAP, because tomorrow is very near.

Techzing interview

Earlier this year I launched my book on hacker news which resonated very positively with the hacker crowd.  This HN exposure landed me an  interview on the TechZing podcast  to discussed my textbook project. Even though it was an hour and a half long interview, there were a some things that we didn’t get to discuss. I want to take the moment now to write down my observations about the textbook business and the educational market.

This blog post is organized with the best stuff at the top so feel free to trail off at any point.


The most important things I’ve learned about the textbook business:

  1. Writing is tough, but writing down lecture notes after a lecture is easy.
  2. Teaching students is gold. By interacting with your students 1-on-1 you get feedback on your explanations.
    If you are lucky you will get a “Sorry, I didn’t get that”, which allows you to iterate.
  3. People still appreciate the printed book. Some people are willing to pay good money for a PDF.


Print-on-demand and eBook technology allow for everyone to publish and sell books. This is a revolution on a Gutenberg scale. One of the forefathers of the Internet/WWW, when asked about the motivation behind his inventions said he did it “so people will be able to earn a living from the fruits of their intellectual labour.”  We have now finally reached this moment where this idea is practical.  Could books be the missing monetization strategy for the Internet?

What have been traditionally two markets—the general audience and the educational market—are now becoming a single market of people who want to learn. Lord knows there are things to learn out there so there is an opportunity for knowledge products for people who want to learn. The key monetization routes will be through selling organized knowledge as textbooks, ebooks, or apps.

I used the term revolution above and I stand by this choice of wording because this is what we call it when a value chain collapses from six-plus levels to three levels. The value chain in the “book business” previously looked like this:

                           __book store 

With print-on-demand the new book business will look like this:

author -- printer -- shipping -- client
^^^^^^                           ^^^^^^ 

Let us call this “author centered” publishing. From now on, authors can expect to get up to 50% of the profits instead of 10% (which could be as low as 5% of the list price). Good times for authors. Incentive-giving-to-move-to-a-new-publisher times.

Even amazon looks like a dinosaur in this context:


Why do you need the warehouse to store all the books? Why not ship from the printer?

There is one element in the traditional publishing value chain that we must keep. Copy editing is actually very important because you really want someone to go through
your writing and fix mistakes in it. You can use your target audience (crowdsource copy-editing), but nothing beats professional services.

OK, so you want to see the future of publishing? Here it is:

 author -- (1) pub.srvc. -- (2) printer  -- shipping -- client
                         _ (3) booksite -- client


The opportunities are (1) for small publishing houses (copy editor + creative person for covers + latex guy) to really come-in and take over the entire market within a couple of years. You could also have larger publishers who focus on marketing the book to certain audiences etc.

Opportunity (2) is for new print-on-demand shoppes to come up (compete with and lightning source). These giants have as their main advantage the established processes they have in place, but how difficult would it be to build an “Espresso Book Machine”-like system based on a quality BW laser printer (think buying toner in gallon tubes at costco 😉 and some automation. The competitive advantage of a small print shop would be that they offer pick up service (0\$ shipping). Currently lulu charges you 6\$ for shipping to Canada (9\$ for 2 books, 12\$ for three books, …, 3+3n.) Shipping within the states is \$5 which is better, but still not free. In particular for printing small books (100-200pp) it would not make sense to order from lulu. They would charge you 5\$ for the printing and another 6\$ for the shipping. Your cost 11\$. If you go to a local print shoppe, they will charge you 7\$ for printing. Same product, half price.

The third opportunity is for high-level editorial services (think curation of content) which would collect book recommendations and let authors and readers interact. Ideally there should be independent “book blogs” for discovery of new content — not marketplaces. Something must be done about the current appstore monopoly. Every app you develop relying on Apple for your distribution is feeding the monster at 30%. Every web app you develop based on Google or FB apis could stop working tomorrow if the API is retired. Go get hosting somewhere and build your own website. Don’t depend on anyone. Okay sorry I got a little off the topic of textbooks. Let’s get back on topic.

I was telling you guys about the book and stuff from the interview. One thing which we talked a lot about was the hacker news launch.

The HN launch

I told Jason how surprized I was when I got 30 000 visitors in one day and how I didn’t get up from my chair for one day. There were roughly 7000 people who clicked on one of the modals. Of these 300 people bought the book in print. By the evening of Jan 1st and into Jan 2nd there were also 100 PDFs purchased from gumroad.


I still working out the numbers (conversion rates) and I don’t want to get too hyped up about them (ok ok, 7k –> 300 = 4.3%) because the HN audience is really VERY sympathetic to the product. I am not sure if everyone else on the internet will like it as much. 

(SIDENOTE: I am finding it hard to get the analytics I want for the book pageGA reports analytic en masse so I cannot see what individual visitors did when they came to  the site. I have basic questions I need answers for and it seems like the current state of analytics is very unimpressive (relative to my expectations). Here is what I would like to know:

  1. Which modal my visitors looked at before deciding to continue onto or gumroad?
  2. Which of the 800 people who clicked through to are the 300 that actually ended up buying the book?
  3. Which sections did they read (scroll to and stay for 4secs+)?
  4. What “path” did each visitor follow through the modals? (subquestion: did anyone see the apg-get install mechanics? did anyone see the integral calculus modal? )

Are there solutions for these? I think the only way I can have end-to-end information is if I run the whole show. If I want to have information about converstions I must build my own shopping cart. Wait, we are on the Internet — I can just submit a feature request to support and gumroad support. I am working on the full writeup of the launch experience here which will have more graphs and numbers. (/SIDENOTE)

I got a lot of feedback from the discussion on hacker news. People really like the idea. The tech crowd of Hacker News is precisely the kind of crowd is interested in learning about advanced math and physics. Many programmers learn the about calculus in mechanics at University but never actually understood these subjects. This is way when the no bullshit guide to mass in physics the really wanted and the 29 dollars price range is definitely not an obstacle for them. Several people also asked for a PG 13 version cleaned up with out of cities in the references to park and alcohol. This is definitely something I will look into it because no told jokes need to be about these subjects. We can stick to the political stuff and the joke about the investment banker being dropped off a building.

What is the goal of the book?

The goal of the book and more generally of Minireference Co. is to teach. Teach students how to get rid of the exam stress when they’re doing their studies. If you know the material really well, then there is nothing tricky that the teacher
can do on the final. Understanding trumps memorization any day of the week. A secondary goal is to teach math to adults, grown ups, so they can let go of their math complexes. There is no reason why a forty year old person should avoid conversations about math and feel uncomfortable when their teenage daughter or son asks them about the solutions to a quadratic equation.

The third goal is to prevent the next generation of analytic reminded youth from going into the defence, pharmaceutical and finance sectors, which I consider to be detrimental to society. I grew up listening to Rage Against the Machine and I feel it is my duty to continue their work in educating the next generations about the system. By situating analytical knowledge in the context of the current world geopolitical situation, it is my hope that the next generation of Einsteins, Gates, Pages, and Zuckerbergs will make informed and moral choices. With knowledge comes responsibility, and I don’t want my students to think about the numbers without understanding what the numbers represent in the real world.

Textbook market

There are a couple of intrenched companies in the publishing world (the big five). Mainstream publishers in the educational market produce textbook that are so expensive, that we can talk about a textbook racket. The readers, subject to their teachers authority, are forced to buy specific textbooks, often at an exorbitant prices > \$100. Mainstream textbooks are also too long and full of fluff like full-page photos designed to pad the pages and impress the student with the “high endness” of the 1000-page publication.  Mainstream textbooks are the kind of product which is the signed by committee. They’re thick and boring.

On the other hand there are several positive things about textbooks.  Irrespective of the widened usage of electronic formats, the “book format” remains the primary medium of intellectual discourse, of which textbooks are a subset. Textbooks are old technology, but good technology. Textbook, as a mean for acquiring knowledge, are better than most educational resources produced for the web.  And it’s not just eBooks, print is here to stay because students don’t like the idea of ebooks replacing textbooks.  Having a PDF to go along with your printed textbook is definitely a feature, but not as a replacement.


Business model

The business model for Minireference Publishing Co. is quite simple: we sell math and science textbooks and PDFs. The specifics of the book “container” are not important. What is important and of value is that we offer an “information distillation” service: complicated science subjects are presented and explained in a concise coherent narrative, including all prerequisites. Instead of reading 100 wikipedia pages to learn about calculus in a month, students can read one chapter in the No BS guide and pick up the same material in a week. 


During the interview, I had a chance to give the full story about the genesis of the book. At 7min40sec in the interview, I say how I started from a collection of notes on advanced physics subjects and that at some point decided to make those notes into a book. Jason replies to this jokingly “Wow that is a big jump!” but I totally missed his joke and just kept on blabbing.

Pivot 1: TOO ADVANCED. There are not that many physicists. We need to go for something more mainstream. New product will be a mini-reference book of formulas for all of science.

Pivot 2: FORMULAS ARE NOT ENOUGH to learn. Let’s have the formulas, but add enough context and explanations to explain where the formulas come from and how they are used.

Once you have the idea… It took two years and 200 commits. It wasn’t high intensity work: I just wrote down lecture notes and my favourite explanations after teaching. During the summer of 2012, I worked intensely to tie together and organize all the material into a coherent story with a beginning (solving equations), a middle (use equations to predict the motion of objects in physics), and an end (learn where the equations of physics arise from calculus).


What is special about this book is the deed forms contains a complete dependency graph of topics. Each subject is explain along with all the prerequisite material. 

Another thing special about the book is its conversational tone. The narration in the book switches from serious to joke mode and back to serious again, and is intended to keep the reader engaged.  Everyone needs a little brake after learning pages and pages of formulas… 

Technology used

During the interview, I didn’t get a chance to discuss the technology stack I used to generate the book. The book started as a bunch of text file in dokuwiki. I then used the dokutexit plugin to export the book as LaTeX. 

Another important tool for the production of the book has been to use the text-to-speech tool in Mac OS X for proofreading. It allowed me to catch lots of mistakes and quickly. 

I use for print-on-demand and for the PDF distribution.


Some future directions for the development of the book are:

  • Finish the linear algebra textbook
  • Write Tome II on electricity and magnetism and vectors calculus
  • Future plans: Write a book about probability and stats 
  • Future plans: Make a No BS guide to Python and JavaScript

Speaking of JavaScript I’m currently exploring the using khan-exercises framework so I could offer practice problems on the site.

The main challenges we face right now is marketing the book to a wide audience.

UPDATE: Since the publication of this post, the No Bullshit guide to math and physics has been improved and revised several times. Sales going Okay. Need more word of mouth


Hacker news launch

Two weeks ago, I posted the book on hacker news. There was an tremendous amount of interest on the first day (20k visits in one day!)
and plenty of good (i.e., critical) feedback. With this post, I want to take a moment and record my impressions from surfing the hacker news wave.

Conversion rates

1. Roughly 33000 people showed up on the “product” page.
2. Of these 7000 clicked on at least one of the modals (engagement).
3. About 1761 of them clicked on the “Buy Book” and went
to the print-on-demand site (
4. Of these 264 ordered the book.

The engagement rate is 7000/33000 = 21%.
The percentage of engaged visitors who clicked “Buy Book” is 25% (=1761/7000).
The final step conversion rate is 15% (=264/1761).
Overall we have 0.21*0.25*0.15 = 0.78% conversion from visitor to client.
Is this good or bad?

Perhaps the more interesting metric is the conversion rate
of engaged visitors (clicked at least on one modal) to client,
which is 3.75%.

A back-of-the envelope calculation tells me that my expected earning
per engaged visitor is about 50 cents. I feel confident that I will be
able to find buy some education keywords for

TODO: try mixpanel (GA is a PITA: full path of the referral url plz!), invest and test adwords.

Book product

The book — as a product — works. Even if there are

TODO: fix typos, add math exercises, add physics exercises.

PDF product

Some of the engaged visitors are also going to the PDF: 19% (= 847/4500).
Then there is another factor of 15% = (50+37+19+7+7+3+3)/847 = one week of PDF sales / one week of clicks to gumroad.
Thus 2.8% of engaged visitors went on to buy the PDF.

Overall this means that 6.55% = 3.75% + 2.8% of my engaged visitors go on to become clients.
Now that is cool!

similar stories

Tools used

New landing page

If you visit you will now see a new design which conforms to the standard “book product webpage” format. I am very pleased with the result, which was an attempt to mimic other good book product pages.

The design process took me about three weeks. Most of the time was spent on the copy editing. The ability to “put stuff on the page” you have with html + css is much more powerful that LaTeX. And with webfonts becoming the norm now, one cam make very beautiful sites very quickly.

Check it out:

The web we still have

The facebookification of the Internet brings with it a stupidification of the content that people produce and share.
The old web was about blog posts (long, though-out pieces of writing) which automatically form links to each other (through trackback) so that a conversation can emerge without the need for a centralized service.

Trackbacks are awesome! For example, I can make this post appear on quora if I embed some javascript (their embed code) which will ping the quora server:
Read Quote of Ivan Savov’s answer to Machine Learning: Does Topic Modeling need a training stage when using Gibbs sampling? And why does it work? on Quora

We need to cherish this kind of distributed technology, because it is the way out of the walled gardens. They are the living proof that you can have social without central.

LDA, BTW, is short for Latent Dirichlet Allocation which is a powerful way to classify documents according to the topics they contain.

December launch

I have been promoting and selling the book for the past two weeks art McGill and I have received a lot of good feedback from students. There is no point in thinking about business ideas — you have to go out and talk to clients. In just two weeks, I now have a title (thanks to my friend Adriano), a product line (I made a mechanics only version too) and a good idea of which pitches work and which do not.


NO BULLSHIT guide to MATH & PHYSICS. In just 300 pages, this book covers Precalculus, Mechanics, Calculus I (derivatives) and Calculus II (integrals). All the material is explained in a clear conversational tone. 100% Math and Physics, No filler.

We sold out today. Let’s see what happens tomorrow.

Mechanics explained in seven pages

I finally managed to complete the Mechanics Tutorial which I have been working on for the past couple of weeks. I am pretty proud of the result. The material from the entire Mechanics class is covered in just seven pages. This should illustrate to my future clients that they don’t need to read a 500 page book to learn mechanics.

All we can do now is wait and see if people will get in touch with me.