Thread: Absolute value of imaginary numbers?

Originally Posted by tabstop

I think you've missed the boat completely. |x| is defined as x*xbar, not as "making x positive" or any such -- it finds the length of x.

I've heard of foobar, but I've never heard of xbar? What is it?

In elementary school, you found the absolute value by removing the negative sign if it existed; in high school it became sqrt( x^2 )... Why don't they just tell us the real formula right from the beginning?

Originally Posted by cpjust

I've heard of foobar, but I've never heard of xbar? What is it?

In elementary school, you found the absolute value by removing the negative sign if it existed; in high school it became sqrt( x^2 )... Why don't they just tell us the real formula right from the beginning?

Originally Posted by tabstop

(where xbar is the complex conjugate of x).

Because most elementary school students aren't up on their inner product spaces. (If it comes to that, we haven't gotten to the real definition of | | in this thread yet either -- all we've gotten to are special cases of the general formula. And for that matter, there are an infinite number of norms (this is the 2-norm, but there's also the 1-norm and the 3-norm and the ... and the infinity-norm). See article.

Originally Posted by tabstop

And for that matter, there are an infinite number of norms (this is the 2-norm, but there's also the 1-norm and the 3-norm and the ... and the infinity-norm). See article.

Maybe ancient hieroglyphics would be easier to understand?
My brain just gets a stack overflow when I look at that page.