this is when I wish I'd taken Linear Algebra

[wallwalker]

My Circuits professor likes to assign us problems with variables. As an example, his lecture on Kirchoff's Laws and his homework mostly involve us deriving equations for various things using only variables for voltage and resistance.

I need a good reference on how to solve linear equations using matrices. And on how to take the determinant of matrices above 3x3 with variables (and without LOSING MY DAMN MIND, good grief, that last attempt took me forever and I didn't even finish.)

(I at least hope he posts a detailed answer to this homework question! Because I'd love to know how he used Kirchoff's Laws to derive the equation he asked us to derive. I could easily do it by finding equivalent resistance, but that's not what he wanted. :/)

Comments

[novel_machinist]

Is there a particular part of the linear to matrices that you're hung up on?

[wallwalker]

I think I'm mostly having trouble with the determinant and the time that it takes. (I ended up with a 5x5 matrix, and I thought I had it set up properly, but my numbers just didn't make sense.)

[crankyoldman]

It's the diagonals trick. Linear algebra is full of little tricks based on the placement of things in the matrices in order to turn it into equations. Think of a matrix like a set of coordinates and linear algebra as a way to turn these extradimensional coordinates into a nice linear equation.

When you have variables, you are basically trying to end up with a standard algebra looking equation. Like a + 3 = b + 2. If you follow the rules of what to multiply against what and what to add, you end up with a more solvable relation than a giant ass matrix.

I will warn you it's always a LOT of writing and doodling. It's actually what made it my favorite math class.

Some other examples that MAY help?

I can see why he's using that kind of thing, because matrices make solving systems of equations much easier. If I knew the specific problem I might be able to help more, but yeah hopefully some of this helps? I know that I always needed a lot of examples to start off with to get what the hell was going on.

[wallwalker]

I can post it later (the homework was due last night, so I don't think it's a problem.) But right now I"m hung up on figuring out where the apparent infinite loop in my project code is, and after that I need to write up a lab report on an ALU design for my lab tomorrow. Those are priorities right now.

(ARGH)