# Help me

• Sep 24th 2013, 12:05 PM
soso123
Help me
• Sep 24th 2013, 12:23 PM
Plato
Re: Help me
Quote:

Originally Posted by soso123

What sort of object is $u=(1,-2i,3+i)~?$ Are those complex numbers?

What operation is involved with $|\overline{u}|~?$
• Sep 24th 2013, 01:12 PM
chen09
Re: Help me
Is this for a "several complex variables" class? I checked out the definition of modulus of u in C^3 (just let n=3 for your case):

$|u|=\sqrt{ \sum_{i=1}^{3} {|u|}_i^2}$

where $u_i = x_i + i*y_i$ and ${|u|}_i$ is the usual modulus of a complex number

• Sep 24th 2013, 02:06 PM
Plato
Re: Help me
Quote:

Originally Posted by chen09
Is this for a "several complex variables" class? I checked out the definition of modulus of u in C^3 (just let n=3 for your case):
$|u|=\sqrt{ \sum_{i=1}^{3} {|u|}_i^2}$
where $u_i = x_i + i*y_i$ and ${|u|}_i$ is the usual modulus of a complex number

That again that is just a guess. I don't think that we should have to guess.

Here is a point. If this is about functions of "several complex variables" then it is a slope question.
Because $|\overline{~u~}|=|u|$, what is the point?
• Sep 24th 2013, 02:17 PM
votan
Re: Help me
Quote:

Originally Posted by Plato
What sort of object is $u=(1,-2i,3+i)~?$ Are those complex numbers?

What operation is involved with $|\overline{u}|~?$

I read OP as a complex number problem and u is a vector. If i is a unit vector on the x-axis, the first component is 1 and one of the two other components must be either the unit vector j and k.

I read the components as (1 + 0i), (0 - 2i), (3 + 1i).

The moduli are: 1, 2, sqrt(10).
• Sep 24th 2013, 02:28 PM
Plato
Re: Help me
Quote:

Originally Posted by votan
I read OP as a complex number problem and u is a vector. If i is a unit vector on the x-axis, the first component is 1 and one of the two other components must be either the unit vector j and k.
I read the components as (1 + 0i), (0 - 2i), (3 + 1i).
The moduli are: 1, 2, sqrt(10).

But you are guessing. Why should we have to guess?
We must expect poster to give a minimal amount of information as well as show some effort.
If a poster show some of his/her work, then we have some basis on which to make a reasonable guess.
• Sep 24th 2013, 03:07 PM
chen09
Re: Help me
Here's where I got my point from:

http://www.dms.umontreal.ca/~gauthier/6140.pdf

Just saying. Don't need to reply to my post.
• Sep 25th 2013, 05:14 AM
topsquark
Re: Help me
Plato's point is that there is an ambiguity in the OP's question. His point is well taken...at first blush what the OP is asking is obvious, but as $| \overline{u} | = | u |$ the problem makes no sense to ask. So questioning the OP is a natural step that needs to be taken. Continuing to make guesses at what soso123 was trying to ask is simply a waste of time and effort.

I'd say wait until soso123 comes back to clear this up. If (s)he doesn't then the problem gets dropped.

-Dan