h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Complex Numbers - an Introduction - A25082372
Author: Icy North - U225620

I've written this to try to clarify the scope between Toy Box's entry on Gauss Integers A25022396 (in PR) and an older EG entry on Imaginary Numbers A316739. It's aimed at the novice.

Let me know if this helps, TB.

Icy

Superb Icy. *i* understand completely now

Small point - B & Q should be joined up as B&Q

To me, it looks fine It's rather non-mathematicians opinions which are relevant!

Just one thing, about footnotes. I think you should move some of them around a bit (or change them to parentheses), so that they wouldn't look like exponents. For instance the 6th footnote makes it look like you're looking for a 36th root of g! (No, not 'factorial g' ).

Ok, here gies as far as I was able to follow this (you lost me at the result of the division):

The difference is (11 - 4i) should be -11 for all I know.

(4 - i)(-7 + 3i) = -28 + 12i + 7i + 3 = (-25 + 19i) - I guess it should be written as: (4 - i) x (-7 + 3i) to indicate that you want to multiply?

As for the rest, I can't tell, it went right over my head again.

For the difference: I think you forgot to substract the 'i' bits.

(4 - i) - (-7 + 3i) = (4 - (-7)) + (-i - 3i) = 11 - 4i.

I agree that a multiplication symbol would be welcome.

Oh, and ' the two numbers above': it might be convenient to recall which are these numbers.

I'll get my coat.

Thanks all, I think I've fixed those minor points.

TB, I'd like to link to your Gauss Integers entry - can you suggest a good place to mention it?

Icy

In 'detached from the real worlds', maybe?



Or in the beginning of the 'That doesn't sound useful to me' section, linking from 'particular use in pure (theoretical) mathematics', or from a footnote.

OK, I'll look into that tomorrow.

Gauss Integers mentioned (but I can't add a link until it becomes Recommended). Other links added too.

Anything else?

I replaced my complex numbers link with your entry too. They would appear to require simultaneous recommendation then

'Many of us find anything to do with numbers complex, not to say downright confusing. We fret our way through school learning more arithmetic, algebra and geometry than most intelligent people would need in a lifetime.'

Reminds me of a figure I once I once heard which said that 'x% of the mathematics we get taught at school we never again need for the rest of our lives - so why bother teaching it!?

Wish I can remember what the x% was. It was quite high, somewhere around 60% I think.

A

Just a nitpick: the first person reference shouldn't be in here:

>>OK, it's an impossible answer - if you don't believe me,<<
why don't you just say: OK, it's an impossible answer - 'if you don't believe it,'?

I'll have a search for that percentage, Al - I'm sure I've heard it too.

I'll fix that "me" in the next 5 minutes, Bel.

Thanks TB

Icy

Well, bravo I say. Thoroughly understandable for a divvy like me. And now the Guass integers make more sense too! Thank you.

Good Entry, no nitpicks.

Thanks Matt - much appreciated

*thinks* - next University project: "Maths for the Complete Divvy"

That vwould be´for Matt and me then, I guess.

oh, that's a two part series -

'Maths for the English Speaking Div'

and

'Maths 4 Forrin Peepul'

Most divvies, sorry, non-mathematicians may best know Gauss from the "De-gauss" button you get on old computer monitors. Press this, and you get a very satisfying shudder, and all the hairs stand up on your back.