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