Jan 30, 2009

notational inconsistencies

As a physics student, I find it really annoying when people use so many different (and sometimes unfamiliar) mathematical notations for the same thing. Worse still, there are times when notations clash, causing ambiguity.

Let's take a simple example:
f(x)
Even if I don't say anything about it, people will often agree that it is a function "f of x".

But what about this?
t(1)
Now here's an ambiguity (even if you don't realize it immediately): is that supposed to be "t times 1" (a product of t and 1) or "t of 1" (a function t evaluated at 1)?

Chances are that people don't encounter this very often, since it is often explained whether t is a function or not. However, in physics it is common to mix functions and numbers, because equations work for both.

There are other less noticeable issues as well. Consider the following:
x2
Most people will say this is "x squared", but if you've done any tensor algebra, you'll know that it can also mean "the value of vector x at index 2"

That's the problem: upper indices use the same notation as for powers, which can be ambiguous sometimes. Although powers don't usually occur with tensors, it is still important to keep the notation consistent and unambiguous.

So far I haven't thought of a reasonable solution for this superscript problem, but I have been thinking about the function/bracket issue mentioned earlier.

One thing I had noticed was that parentheses, square brackets, and also curly braces are often used to denote the order of operation. However, I think it's redundant and unnecessary to use all three different kinds of brackets just to do the same thing. It's a "waste", I would call it. Perhaps we could use square brackets for functions instead of the usual parentheses? It is compatible with the typical use of brackets (since functions are sometimes indicated with square brackets, though not as often). So I could say "f(x)" to mean the product of f and x (of course it would be rare to write it like this; it's better to say "f x") while "f[x]" to mean the function f acting on x. I wouldn't call this convention-breaking (since it's fairly compatible with the original notation of functions), but it certainly would be unusual.

There are other cases of ambiguities in math & science. For example, consider "e". "e" is the natural base, but it's also the symbol for the elementary charge, so how do I differentiate them? (Again, it's unlikely that an equation would use these 2 at the same time, but it's still possible.) My subtle solution is to use italics for elementary charge ("e") and upright for the natural base ("e"). It's a very minute difference, but I prefer it this way to avoid confusion.

Similarly, I would use the upright form of "π" to represent the circular constant, and italics for anything else (unfortunately, sometimes it is very difficult to distinguish between upright and italic Greek letters in some fonts). The reason why "π" and "e" get an upright font is because they are very special mathematical constants.

Besides constants, I also prefer to use the upright "d" for derivatives to avoid confusion with variables or functions that are named "d". There are quite a few textbooks that actually use this convention.

I really wish there was a specific "committee" of some kind that regulates mathematical syntax and conventions (sort of like the IUPAC for chemistry, or SI for scientific units).

Jan 25, 2009

filler post

The past week has been a series of awful time management, which is why I can't scoop myself an hour to work on my blogs. Nonetheless, I'll try to summarize the whole week with a short 15 min post.

The classes began on Jan 12, as I may have mentioned earlier. This 17-credit semester consists of 7 courses, of which 3 are physics (including a lab), and the remaining 4 being chemistry, biology, math, and computing.

The great things are: I get to learn cool new physics, math, and a new programming language (i.e. C). The annoying things are: lot's of written homework. I can't stress that enough: written homework. I don't like written homework; I prefer to type things out neatly rather than hand-in a page containing 20% cancellations and pencil-carbon smudges.

Besides the 2 physics and math classes that require written homework, there's a "lightweight" single credit computing class that I stumbled by chance: an opportunity to learn some C, and perhaps gains some real programming skills. I mean this is the first time I get to do anything in C; normally I'd be in a persistent fear of C (or C++, both are pretty scary and nasty) because I'm clueless as to how I can do anything useful in those languages. How do I write a file? How do I draw a line? How the heck to I even construct a window? (I must have been too dependent on GUI-based programming like MS Visual Studio.)

Those are questions that can be hopefully answered, or at least I would know how to answer them. I really need to get into a mood of programming... it's been months since I'd wet my hands with some real programming.

Okay, that's my filler post. I really hope I can do some better time management next week, considering the "dormant" physics lab will begin classes on Tuesday, which implies lab reports and more lab reports.

Jan 14, 2009

twin para-dogs

I can't help notice the fact that "paradox" sounds surprisingly similar to "para-dogs". Funny, I could've made a pun out of it, but I'll save the embarrassment.

Back to topic: Spring semester just started on Monday, so my regular routines come back into play, which means I feel a lot more organized now. However, this means there's plenty of homework and assignments to keep track of (and not forget).

The first thing that frustrates me in a semester is the textbooks. Buying textbooks is a pain because they always cost a lot more than you'd typically pay for an average book. This time, there is the additional problem of a book (Calculus III, Marsden & Weinstein) that isn't available in bookstores, so I had to order them.

Besides all the book chaos, my physics classes quietly began on Monday. Today, I suddenly got a big surprise: I'm already starting to learn special relativity in my modern-physics class, yet I never thought about it in this light. (And hence the title of this post: the twin paradox concerning special relativity.)

Unlike the one for last semester, the calculus class for this semester requires us to hand-in our assignments weekly, which means no slacking-off for me. In addition, there are also written assignments required for my classical-dynamics class. On top of that (and all the other electronic homework on LON-CAPA and OWL), I have a physics lab, so I'll have lab reports to work on (again).

Still, I hope to have a great Spring semester.

Jan 3, 2009

start of another year

Oh it's a new year. Didn't felt like much though; the extra leap second gained felt like nothing.

The new year of 2009 has already begun, which means I'm not too far from Spring semester (a week away!). Thinking back, I could've been a bit more productive during this break.

I wonder if I'll ever grasp C++ (I got a bit of my programming spirit back recently). I wonder how the next semester will go. I wonder how the International Year of Astronomy would be. Lot's of anticipation, and lot's of doubts.

Nonetheless, I wish everyone happy new year (despite being 3 days late).

Also, I thought I could post some funny links:
Have a grand new year!