Welcome,
Guest
. Please
login
or
register
.
Did you miss your
activation email
?
1 Hour
1 Day
1 Week
1 Month
Forever
Login with username, password and session length
Home
About
Team
Rules
Stats
Status
Sitemap
Chat
Downloads
Forum
News
Our Projects
Major Community Projects
Recent Posts
Unread Posts
Replies
Tools
SourceCoder3
Other Things...
Omnimaga Radio
TI-83 Plus ASM File Unsquisher
Z80 Conversion Tools
IES TI File Editor
Free RAM areas
Comprehensive Getkeyr table
URL Shortener
Online Axe Tilemap Editor
Help
Contact Us
Change Request
Report Issue/Bug
Team
Articles
Members
View the memberlist
Search For Members
Buddies
Login
Register
Omnimaga
»
Forum
»
General Discussion
»
Other Discussions
»
Math and Science
»
math stuff
« previous
next »
Print
Pages: [
1
]
Go Down
Author
Topic: math stuff (Read 5967 times)
0 Members and 1 Guest are viewing this topic.
squidgetx
Food.
CoT Emeritus
LV10
31337 u53r (Next: 2000)
Posts: 1881
Rating: +503/-17
rawr.
math stuff
«
on:
June 17, 2010, 06:22:40 pm »
k so basically I was wondering if proof by induction is valid if, for the first step, you prove for x=0 instead of x=1.
Using domino logic, it's really a matter of whether you decide to start counting from 0 or 1 (which is where I got the idea to ask you guys....
kthxbai
Logged
Read my webcomic!
|
My SoundCloud
Projects:
[url=http://www.omnimaga.org/index.php?topic=5988.msg117813#msg117813]Check out the demo now!
- Current progress: battle engine and stuff
Proud author of:
Cuberunner
|
SpaceDash
|
The Psyche
|
XXEdit
|
AxeSynth
|
StickNinja
|
Gravity Guy
|
Embers:Phoenix
|
Zombie Gun
Axe: Need help optimizing?
User of Axe | zStart | TokenIDE | CalcGS | MirageOS
meishe91
Super Ninja
LV11
Super Veteran (Next: 3000)
Posts: 2946
Rating: +115/-11
Re: math stuff
«
Reply #1 on:
June 17, 2010, 06:24:25 pm »
I'm not exactly sure what you are asking...could you please explain more?
«
Last Edit: June 17, 2010, 06:25:05 pm by meishe91
»
Logged
Spoiler
For
Spoiler
:
For the 51
st
time, that is not my card! (Magic Joke)
calcdude84se
Needs Motivation
LV11
Super Veteran (Next: 3000)
Posts: 2272
Rating: +78/-13
Wondering where their free time went...
Re: math stuff
«
Reply #2 on:
June 17, 2010, 07:06:23 pm »
Yeah, it should be valid.
meishe: squidgetx is referring to proofs by induction, which typically work by proving that statement p is true for x=1, and p is true for x+1 if p is true for x. Therefore, p is true for all natural numbers. He's asking if it's valid to start at x=0, rather than x=1. I said yes
Logged
"People think computers will keep them from making mistakes. They're wrong. With computers you make mistakes faster."
-Adam Osborne
Spoiler
For
"PartesOS links"
:
I'll put it online when it does something.
meishe91
Super Ninja
LV11
Super Veteran (Next: 3000)
Posts: 2946
Rating: +115/-11
Re: math stuff
«
Reply #3 on:
June 17, 2010, 07:22:10 pm »
Ah ok. Well i don't quite know still but I'll look it up. Thanks though.
Logged
Spoiler
For
Spoiler
:
For the 51
st
time, that is not my card! (Magic Joke)
squidgetx
Food.
CoT Emeritus
LV10
31337 u53r (Next: 2000)
Posts: 1881
Rating: +503/-17
rawr.
Re: math stuff
«
Reply #4 on:
June 17, 2010, 08:07:30 pm »
Thanks
Meishe; quick explanation of proof by induction using domino's....heh heh
Statement 1: The 1st domino falls over
Statement 2: If a domino falls over, the one after it falls over
Therefore, all the dominoes fall over
So in proofs by induction, you prove that a statement is true for 1 (or 0, as calc84se says), then assume it is true for some constant, k, and the prove it's true for k+1
Calc84se, if what you've said is true, then I just proved Euler's formula w/o any calculus
(kinda random I know but ever since I saw that xkcd where e^(pi i)=-1 I've never been completely satisfied with the explanations (mainly b/c i'm not as advanced in calculus yet >.<)
Logged
Read my webcomic!
|
My SoundCloud
Projects:
[url=http://www.omnimaga.org/index.php?topic=5988.msg117813#msg117813]Check out the demo now!
- Current progress: battle engine and stuff
Proud author of:
Cuberunner
|
SpaceDash
|
The Psyche
|
XXEdit
|
AxeSynth
|
StickNinja
|
Gravity Guy
|
Embers:Phoenix
|
Zombie Gun
Axe: Need help optimizing?
User of Axe | zStart | TokenIDE | CalcGS | MirageOS
calcdude84se
Needs Motivation
LV11
Super Veteran (Next: 3000)
Posts: 2272
Rating: +78/-13
Wondering where their free time went...
Re: math stuff
«
Reply #5 on:
June 17, 2010, 08:30:42 pm »
Since we're talking about math, do you mind showing me your proof? I'd like to see it personally, as I'm always interested to learn something new about math.
Logged
"People think computers will keep them from making mistakes. They're wrong. With computers you make mistakes faster."
-Adam Osborne
Spoiler
For
"PartesOS links"
:
I'll put it online when it does something.
Quigibo
The Executioner
CoT Emeritus
LV11
Super Veteran (Next: 3000)
Posts: 2031
Rating: +1075/-24
I wish real life had a "Save" and "Load" button...
Re: math stuff
«
Reply #6 on:
June 17, 2010, 08:34:41 pm »
The way proofs by induction work, is that you have to "pretend" that a function works and then if this assumption leads to a truth then you can conclude that you were right in assuming the original function. The dominoes example would be more like this:
1. The first domino has fallen over.
2. Suppose that Nth has fallen over
3. You can show that if that is the case, then the N+1th domino will fall over
4. Since if this is true for the Nth domino, then it is true for the N+1th domino, and it is true for the first domino, they you can say that all dominoes past the first position will fall over.
Logged
___Axe_Parser___
Today the calculator, tomorrow the world!
squidgetx
Food.
CoT Emeritus
LV10
31337 u53r (Next: 2000)
Posts: 1881
Rating: +503/-17
rawr.
Re: math stuff
«
Reply #7 on:
June 17, 2010, 08:45:18 pm »
......Shat.
I kind of made an assumption that's not quite valid
Here it is though, if you want to see it
Ok, so Euler's Formula states
e^(xi)=cos x + i sinx (or cis x)
Step 1: prove for x=0
e^0i= cos0 + i sin0
1=1+0i
1=1
Step 2 Assume true for x=k
e^(ki) = cis k
Step 3 Prove for x=k+1
e^(k+1)i=cis(k+1)
e^(ki+i)= //distribute i
(e^ki)(e^i)= // exponent property
(cis k)(cis 1)= // here's where i mess up. In my original proof, I did induction the standard way, except it's really hard to prove e^i=cis 1, so I just kind of assumed that it was true and used it here to sub it in as e^i=cis 1
(cos k +i sin k)(cos 1 + i sin 1)= //expand
cos k cos 1 + i sin 1 cos k + i sin k cos 1 + -1 sin k sin 1 //multiply out
cos k cos 1 -sin k sin 1 + i (sin 1 cos k + sin k cos 1) = //re order terms
cos (k+1) +i sin (k+1) //recognize cos and sin sum formulas
cis (k+1) =cis (k+1)
Subbing in pi gives e^ (pi i) = cos pi + i sin pi
= -1 + 0i
= -1
I always do this, I get an idea, I get lazy, skip a step, and then realize that it threatens the whole integrity of the proof >.<
Logged
Read my webcomic!
|
My SoundCloud
Projects:
[url=http://www.omnimaga.org/index.php?topic=5988.msg117813#msg117813]Check out the demo now!
- Current progress: battle engine and stuff
Proud author of:
Cuberunner
|
SpaceDash
|
The Psyche
|
XXEdit
|
AxeSynth
|
StickNinja
|
Gravity Guy
|
Embers:Phoenix
|
Zombie Gun
Axe: Need help optimizing?
User of Axe | zStart | TokenIDE | CalcGS | MirageOS
calcdude84se
Needs Motivation
LV11
Super Veteran (Next: 3000)
Posts: 2272
Rating: +78/-13
Wondering where their free time went...
Re: math stuff
«
Reply #8 on:
June 17, 2010, 08:53:40 pm »
Not valid, then. Too bad...
It would have been amazing (and I would've been very happy for you) if that had worked.
Oh well, it was a nice try. Better luck next time. At least the answer to your original question was yes.
Have fun with math, anyway.
Logged
"People think computers will keep them from making mistakes. They're wrong. With computers you make mistakes faster."
-Adam Osborne
Spoiler
For
"PartesOS links"
:
I'll put it online when it does something.
Print
Pages: [
1
]
Go Up
« previous
next »
Omnimaga
»
Forum
»
General Discussion
»
Other Discussions
»
Math and Science
»
math stuff