Category: Links

How Many Decimals of Pi Do We Really Need?

Marc Rayman, director and chief engineer for NASA’s Dawn mission, explaining why NASA uses 3.141592653589793 (“only” 15 decimal places) for its most accurate calculations:

Earlier this week, we received this question from a fan on Facebook who wondered how many decimals of the mathematical constant pi (π) NASA-JPL scientists and engineers use when making calculations:

Does JPL only use 3.14 for its pi calculations? Or do you use more decimals like say: 3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067982148086513282306647093844609550582231725359408128481117450284102701938521105559644622948954930381964428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273724587006606315588174881520920962829254091715364367892590360

[…]

The most distant spacecraft from Earth is Voyager 1. It is about 12.5 billion miles away. Let’s say we have a circle with a radius of exactly that size (or 25 billion miles in diameter) and we want to calculate the circumference, which is pi times the radius times 2.

Using pi rounded to the 15th decimal, as I gave above, that comes out to a little more than 78 billion miles. We don’t need to be concerned here with exactly what the value is (you can multiply it out if you like) but rather what the error in the value is by not using more digits of pi. In other words, by cutting pi off at the 15th decimal point, we would calculate a circumference for that circle that is very slightly off.

It turns out that our calculated circumference of the 25 billion mile diameter circle would be wrong by 1.5 inches. Think about that. We have a circle more than 78 billion miles around, and our calculation of that distance would be off by perhaps less than the length of your little finger.

Apple to Build out Own Cloud Infrastructure

Mark Bergen, reporting for Recode on reports that Apple is shifting some of its cloud infrastructure from AWS to Google:

In its bid to raise its name in cloud computing services, Google nabbed a big-name customer: Apple. The iPhone maker recently started storing portions of its iCloud and services data with Google’s cloud platform, according to sources familiar with the deal.

It’s a win for Google, which is gunning for larger companies as cloud customers. But it might be short-lived, as it looks like Apple is also simultaneously building out its own system to bring data stored on its millions of devices in house.

Currently, much of Apple’s iCloud luggage sits with Amazon Web Services, the leading cloud provider by a long mile, and also with Microsoft’s Azure. CRN, the publication which first reported the news, claims that Apple is trimming its reliance on AWS by turning to Google. At minimum, Apple would seem to be adding Google to the mix.

[…]

Then there’s Apple’s next step. Morgan Stanley, in a note last month, laid out the tea leaves: Apple has announced three data centers opening soon and spent an estimated $1 billion last year on AWS. It’s a logical move for Apple if it wants more independence from its tech rivals. And it’s one Apple should make to store the growing media libraries from its mobile, TV and TBD products.

According to a source familiar with the matter, Apple already has a team working on this; it’s known internally as “McQueen,” as in Steve. It’s unclear if that project will materialize or when. But a source tells Re/code that the codename refers to Apple’s intent, sometime in the next few years, to break its reliance on all three outside cloud providers in favor of its own soup-to-nuts infrastructure.

The move to their own data centers falls in line with Tim Cook’s longtime refrain:

“We believe that we need to own and control the primary technologies behind the products that we make.”

It is interesting that Apple uses all three major cloud providers now, but it does give each one the edge to say both: Apple iCloud is hosted here, but not to be able to say they are the primary iCloud hosting provider.

Indies And The App Store

Brent Simmons:

Rene Ritchie, in What no indie developer wants to hear about the App Store, writes:

Big apps get all the attention these days, just like big movie, music, or book releases — or big toy releases — and indies get what little is left, when there’s even a little left. The App Store is big business, and that’s how big business works. Only our nostalgia keeps us thinking otherwise. Just like our nostalgia for the corner store in the age of online and big box.

On this same subject, Ben Thompson’s Why doesn’t Apple enable sustainable businesses on the app store? is worth a re-read.


Obviously some companies are doing well — such as Omni, where I work — selling productivity apps on the App Store.

And indies would do better than they are right now — possibly much better — if the App Store had trial versions, upgrade pricing, and a faster and better review process. (And the Mac App Store should make sandboxing either less onerous or, preferably, optional.) (And — since I’m listing the ponies I want — it would help if Apple took something like 10% rather than 30%.)

But a couple other things are true:

There was never a golden age for indie iOS developers. It was easier earlier on, but it was never golden. (Yes, some people made money, and some are today. I don’t mean that there were zero successes.)

And there’s a good chance that many of the people you currently think of as thriving iOS indie developers are making money in other ways: contracting, podcast ads, Mac apps, etc.

I agree with Brent on a lot of points here. As an indie app developer, there are moments when you wish some things were done differently.

Chuq Von Rospach on Fixing the Apple App Store

I’m a strong believer that the indie developers are where the innovation comes from, not to mention the next generation of experts on the platform, and that it makes sense to invest in supporting them beyond what the revenue their apps will return through sales on the platform, but in all honesty, the revenue numbers and analytics make that a tough sell, and Apple is likely in that place where there are 300 proposals on the project list for the next year, and resources for 50 of them, so how do you choose which ones make the cut?

Eric Schmidt spotted snapping pics with an Apple iPhone

Apple Insider:

Former Google CEO and current Alphabet Executive Chairman Eric Schmidt was in South Korea for a press event this week, where he was spotted taking pictures of the event using an Apple iPhone instead of a Google Android handset. […]

While the sight of Schmidt using an iPhone, and not an Android device, may come as a surprise to some, it’s not entirely unexpected — Schmidt continued to use a BlackBerry well after the launch of Android, candidly admitting he preferred the handset’s physical keyboard.

Wonder what the story will end up being here…

Use Data McFly to build a real-time Todo app

If you like to keep organized, then you want a todo app. In this tutorial, we’re going to build a simple real-time todo app.

This app will consist of four functions:

  1. Add new items to do
  2. Mark items as done
  3. Mark items as not done (undo)
  4. Delete items

This is simple functionality, but it is exactly what a todo app is all about, and can run anywhere as this will consist of an html file, a javascript file and some very basic css.

All you need to build your todo app is a free Data McFly account. There’s no server-side programming needed for this app.

This was a quick, fun tutorial to write. Showing how to build a simple todo list app using Data McFly.

Build a real-time SMS call center with Data McFly and Twilio

Do you want to know one of the beautiful things about Data McFly? It integrates really easily with other services.

In this article, we are going to walk through using Data McFly and Twilio together to build a real-time SMS call center.

This could be used as a customer help desk where customers send a text message for help and an agent sends a reply back from their web browser.

The actual phone work will be handled by Twilio, and Data McFly will store the data and display the chats in real-time. We’ll use node.js to send and receive the text messages and an HTML frontend to handle the actual chatting.

I decided this week to give myself the task of building a real-time SMS call center that used Data McFly for the data handling and real-time communication, and Twilio for the phone work.

The end result turned out pretty well.