Question

is there any other way to talk about matrix sizes other than rows x columns that people actually use?

Answer 1

Not that I know of, its really important to know how many rows and columns there are in a matrix, because without that knowledge, the statement:
\[AB= C\]
could make sense or be completely undefined.
You would need to know that A is a nxm matrix, B is a mxp matrix, and their product is C, a nxp matrix.

Answer 2

it'd be mxm though right? using your notation?

Answer 3

sorry dont worry

Answer 4

(nxm)(mxp)
The matrix multiplication is defined since the number of columns in A matches the number of rows in B (the m's). What produced is whats left: an (nxp) matrix.
Numerical examples:
(4x2)(2x3) gives 4x3

Answer 5

i just did it again, cause you were typing an explanation, then proved it

Answer 6

thanks

Answer 7

ah, alright, just as long as you get it, its cool :P linear algebra is one of my favorite subjects, so im glad someone is asking questions about it lol

Answer 8

you americans have crazy subject names

cant you just say stuff on matrices is subject heading :Matrices

:)

Answer 9

i mean really, 4*3 and 3*4 matrices is hardly the same right? or aren't i understanding it still....

Answer 10

lol

Answer 11

haha, well, im getting ready to take a class called "Matrix Theory"
and yes you are right, they arent the same. They have the same number of "elements" in the matrix (12), but they live in different worlds

Answer 12

oh good, so im not necessarily going crazy in this case.