# Thread: Maths notation

1. ## Maths notation

Greetings, I am a new member and I've come here to get some help with maths.

I have a degree in Chemistry and work as a chemist in industry, but I'm also studying to make a transition int chemical engineering. This means lots of advanced applied mathematics, and I'm having trouble understanding my notes. Can you help with the following points, as my tutor is next to useless at the moment.

1. A matrix is denoted by a letter e.g. A with a line underneath (can't really show on here easily) but what is meant by A with a double underline?

2. What is meant by this:

E (as in "is an element of") R^nxn
The R is a very ornate looking letter, a bit like old calligraphy. Very odd.

I nreally hope someone can help.

Thanks

2. 1. A matrix is denoted by a letter e.g. A with a line underneath (can't really show on here easily) but what is meant by A with a double underline?
I have never seen that notation, could you give the tile and author of the text you're using in that class?

E (as in "is an element of") R^nxn
The R is a very ornate looking letter, a bit like old calligraphy. Very odd.
Is it something like $\mathbb{R} ^{n \times n}$ or $\mathcal{R} ^{n \times n}$ ? If it's one of these, it usually means an $n \times n$ matrix with real entries.

3. The problems come in the lecture notes, not a specific text. I'm studying by distance learning as the university is 200 miles away from where I live - the only one in the UK that delivers the course I want in distance learning form. The traditional engineering content is easy to understand and fun to study but the maths... !

The notes for this module are presented as powerpoint slides which are fine with a narrative eg in a face to face lecture, but I don't have that sitting in my apartment/flat in front of the laptop, and to compound the issue I don't have any grounding in engineering mathematics. Bit of a steep learning curve at the moment!

I suspected it meant real numbers so thanks for confirming that - those two symbols you put up are both used.

The double-underscore thing is used in the context of applying the Newton method to a system of linear equations in 2 dimensions, i.e. evaluating F(x) and F'(x) where F is a matrix of functions in x. The equation is written as F'(x) = J(x) with F having a single underscore (standard matrix notation) and J having a double underscore. All I can think is that this is standard matrix notation for the deriviatve of a matrix of functions....