SI_Bot

A common complaint I get is that I don't respect significant figures (sigfigs).

This is partly true because I make assumptions about the significance of the figures posted by comment authors. The core problem is that submitters are very rarely respecting sigfigs, and it's compounded by the fact that even where users would like to respect them, there is no easy way to designate significance on Reddit.

So the assumptions I make are:

1. Every digit left of the decimal point is significant. So 1000 has four sigfigs.
2. Every digit right of the decimal point is significant except for values between 0 and 1. So 1.0 has two significant d

Probably the most controversial feature of this bot is that it quotes the original comment with the unit conversions included inline.

I've gotten a lot of attention on this feature specifically. There's been fan mail, hate mail, and suggestions on how to improve it.

Other bots just list conversions, and especially if that list of conversions is not the top-voted responding comment, it can be troublesome to move back and forth between the two comments figuring out how the units are being used.

At the same time, for very short comments, or comments with only one conversion, it doesn't accomplish a lot, and for very long comments, it can be a lot of wasted space. Most of the hate mail fo

Pounds, ounces, and the like are a measure of weight, Kilograms are a measure of mass, and Newtons are a measure of force.

Weight is rarely useful from a scientific perspective, because it conflates the concept of mass and force for most uses. More specifically, weight is the force on an object due to gravity, which is strongly associated with its mass.

For legal and commercial purposes, weight is typically considered to be mass (as if measured at sea level on Earth). Most humans in typical conversation also tend to mean mass when they refer to weight (though for non-scientists the ideas of mass and force-due-to-gravity are not usually well separated).

More often than not, it's probably

u/sje46 decided to see what the upper bound for SI_Bot's math processing is, discovering I have a limit in the 10^675 range. The math library I use is arbitrary precision, the problem is actually the routine used to format the number for display (adding commas and displaying particular decimal places).

For context, the angstrom is a unit we use to measure the size of atoms. The observable universe is about 10^36 angstroms across. There are only 10^80 atoms in the entire observable universe. 10^675 is a REALLY big number, and not particularly likely to be useful even for particle physicists.

Relatedly, I possess divide-by-zero absorbing crumple zones, so my fraction parsing won't b

Gallon is a tough unit to convert, because there are a number of competing definitions for the gallon. Even those definitions have in the past disagreed with themselves inconsistently. For example, there was a while where the size of a gallon depended on what you were measuring. A gallon of wine was ≈ 3.79 L, a gallon of ale was ≈ 4.62 L, and a gallon of corn was ≈ 4.405 L.

In modern times, gallons are more consistent, but there is still a distinction between the US and UK.

A modern imperial gallon is 4.54609 L, while a modern US gallon is 3.785411784 L.

The UK is actively attempting to phase out the use of the imperial gallon, and has been since 1995 or so (albeit with limited success

I will convert X'Y" as shorthand for X feet Y inches, but I will not convert X' or Y" by itself. This is because it generates too many false triggers when someone has a number at the end or at the start of a quote.

I often get the difference between ounces and fluid ounces wrong. Ounces is a measure of weight, while fluid ounces is a measure of volume.

Mostly this is because although "ounces" is used interchangeably in conversation with "fluid ounces," it is not correct or accurate to do so. Your beverage may weigh 12 ounces, but it's a lot more likely it's 12 fluid ounces in volume. If you say "12 fluid ounces," I'll convert this for you correctly, but if you just say "12 ounces," I have no way of knowing which you mean, so I'll trust you used the right variant (even though that's pretty rare when it comes to conversations about fluids).

The good news is that I convert ounces into grams, and even

It's common to get complaints about the unit Ton or Tonnes.

There are three measures which are similar sounding, and two even have the same name as each other.

• Ton (US Short Ton) = 2000 pounds = 907.1847 kg
• Ton (UK Long Ton) = 2,240 pounds = 1,016.047 kg
• Tonne (Metric Ton) = 1,000 kg = 2,204.623 pounds

I convert "Ton" into the US Short ton because doing a mental estimation for this value is hardest, and not only is it extremely difficult for a bot to know which one was meant, but often it's not even possible to know from the context which one the author meant.