# A question about a scientific notation

Joined Jul 7, 2009
1,583
I was looking up some information on wikipedia and came across an unexplained notation on the wikipedia page for scandium. If you look at the vapor pressure temperature for 100 Pa, you see it's "(2006)", for 2006 K. My question is: what do the parentheses mean?

In accounting, the parentheses mean a negative number. In my past scientific experience, using parentheses like this has meant either an approximate number or an extrapolated/interpolated number as opposed to a measured number.

But I'm at a loss for figuring out what the wikipedia pages mean with this notation. I've perused their style guides, but have come up empty.

Does anyone know what exactly they mean with this notation?

#### steveb

Joined Jul 3, 2008
2,436
Does anyone know what exactly they mean with this notation?
I'm not sure, but my guess it that it is one of those confusing typesetting blunders.

I feel your pain. The numbers below 100 Pa don't have parentheses, while the others have them. The fact that they are different make you wonder if there is special significance. Maybe there is (maybe means uncertain number), or maybe the typesetter was careless.

Yesterday, I spent an hour trying to find out what a bolded italic capital letter O means in matrix notation. It was not defined in the paper and showed up near a capital I matrix, which also was not defined, but is obviously the identity matrix. I was convinced that this was an accepted convention that I just didn't know. It turned out that this is supposed to be a Zero matrix (matrix with all zeros in it). Why the typesetter didn't use a bolded zero is beyond me.

#### steveb

Joined Jul 3, 2008
2,436
By the way, I had an engineering professor who came from Germany. He always wrote numbers with parentheses around them. This resulted from his way of expressing scientific notation without the times symbol. In other words he would write $$(3.4)\;10^4$$ instead of $$3.4\times 10^4$$. So, if the power of ten was zero, he wouldn't write it, but would keep the parentheses, and a number like 5 was written on the blackboard as (5).

Probably unrelated to your question, but I thought I would mention it.

Joined Jul 7, 2009
1,583
Hi, Steve -- No, it's not a blunder -- there are too many uses like this across a bunch of wikipedia web pages (I'm gathering data to produce a periodic table I've wanted for a few decades). For example, look at the vapor pressures page at the element yttrium (atomic number 39) here. It's systematically denoting something, but they don't define what it is. Also note the poor notation of "T/K", which means temperature in units of kelvin; however, the "/" character is almost universally used for division (and frequently in units), so it's a poor choice on someone's part. We humans can puzzle it out, but imagine the software effort it will take to get an AI to correctly interpret the page...

This is one of the problems in using symbols -- authors can get too parochial in their writing and assume that the notations they use are universal. Alas, this is most definitely not true and all it does is cause confusion and lost time to others. Your experience with the matrix notation is a case in point. And people don't change because they don't feel the pain of their readers...

#### BillO

Joined Nov 24, 2008
999
IIRC, it may be the value associated with the isotope with the longest half-life in cases where there is a difference in that value between the isotopes.

Joined Jul 7, 2009
1,583
I don't think that's it either, as the notation is used on stable elements. And sometimes in the vapor pressure data, the parentheses will appear for a couple of values, but not all of them.

#### Kermit2

Joined Feb 5, 2010
4,162