Clash

general recent conversations

$Mathematics$ Mathematics

Associated with Math.SE; for both general discussion & math qu...

Clash

Jun 14, 2015 10:51

Thanks @evinda, I just posted the question and realized it's a diagonal made out of blocks of matrices, so blkdiag did the trick on Matlab! Thanks!

Clash

Jun 14, 2015 10:13

Hey guys, what is this function supposed to do? $diag(A_1, A_2)$ thanks for the help! I thought the diag function would just return a matrix with $0$s everywhere except on the diagonal, but the comma is trying me on a loop

Clash

Sep 25, 2014 19:42

Hi, could anyone tell me what's an m-diagonal matrix is? Is this being both an M matrix and a diagonal matrix?

Clash

Jul 20, 2013 17:28

with $\varphi(N) = (P-1)(Q-1) = 10*16 = 160$

Clash

Jul 20, 2013 17:28

As this is a exercise about RSA, I can do a trick
$64^107 mod 187 = 8^(214 mod \varphi(N)) mod 187$

Clash

Jul 20, 2013 17:26

@PeterTamaroff thanks, you are correct, there is no faster way than using Euklid

Clash

Jul 20, 2013 17:19

@PeterTamaroff of course I don't mean Wolfram...

Clash

Jul 20, 2013 17:19

I'm looking for tricks like $45^5 mod 47 = (-2)^5 mod 47$

Clash

Jul 20, 2013 17:19

There must be a faster way

Clash

Jul 20, 2013 17:18

How am I going to put these two equations together at the end?

Clash

Jul 20, 2013 17:16

how am I going to put these two equations together at the end?

Clash

Jul 20, 2013 17:15

@PeterTamaroff I don't know what you mean with $\varphi(187)$

Clash

Jul 20, 2013 17:14

Are there any tricks for solving $64^{53} mod 187$?

Clash

Jul 15, 2013 17:17

wasted 1 hour on this crap and it was right on my face

Clash

Jul 15, 2013 17:17

Charlie, thanks for the help... i've found my mistak

Clash

Jul 15, 2013 17:04

I've posted it here
http://math.stackexchange.com/questions/444319/calculating-eigenvectors-from-the-identity-matrix

Clash

Jul 15, 2013 17:02

i want to calculate the eigenvectors of the identity matrix, it shouldn't get any simpler than that

Clash

Jul 15, 2013 17:01

it is really simple what I want

Clash

Jul 15, 2013 17:01

Clash

Jul 15, 2013 16:57

For the eigenvalue 1, it gets me the null matrix. For -1 I get independent lines, which results on the eigenvector null. I must be doing something wrong

Clash

Jul 15, 2013 16:56

I want to calculate the eigenvectors from the identity matrix

Clash

Jul 15, 2013 16:55

however I'm stuck when the lines aren't multiple of eachother

Clash

Jul 15, 2013 16:55

like on math.stackexchange.com/questions/364484/calculate-eigenvectors (2nd one you sent me)

Clash

Jul 15, 2013 16:55

well yes, it works pretty well with matrices that end up with linear dependent rows

Clash

Jul 15, 2013 16:52

I'm quite stuck on how to calculate eigenvectors. I've been trying to do $(A-\lambda I)x=0$ and failing miserably. I have for the example the Identity Matrix 2x2, $I_2$. The eigenvalues are $1$ and $-1$. For the eigenvalue $1$ I will get the null matrix. How am I supposed to get a eigenvector from that?

Clash

Jul 15, 2013 16:48

hey guys, can I ask a dumb question about eigenvectors?

Clash

Aug 25, 2012 15:28

oh ok, thanks! I thought someone could instantly notice based on the original matrix that all eigenvalues could only be 0 because there are two linear dependent lines

Clash

Aug 25, 2012 15:25

is this considering I'm not a computer? what should be faster?

Clash

Aug 25, 2012 15:22

yeah sorry, i ment deduction not assumption

Clash

Aug 25, 2012 15:22

how can you from there say that it's eigenvalues are all 0?

Clash

Aug 25, 2012 15:22

yeah like you said, the original matrix's columns are the same (inner and outer)

Clash

Aug 25, 2012 15:21

can i make assumptions based on the original matrix?

Clash

Aug 25, 2012 15:21

yes, that is correct, i am searching for the characteristic polynomial

Clash

Aug 25, 2012 15:20

if there was a single linear dependent line on the matrix with x, then i could say the det is 0 and there is no eigenvalue, right?

Clash

Aug 25, 2012 15:19

I can see there are two linear dependent lines on the original matrix, but does this matter if it's without the x?

Clash

Aug 25, 2012 15:14

thanks jasper!

Clash

Aug 25, 2012 15:13

is there any easier way looking at the first 4x4 matrix that it is in fact x^4?

Clash

Aug 25, 2012 15:12

god damn, never mind... it's because I had this: -(1-x)(x^3+x^2+x) - x and I could have sworn that couldn't be x^4

Clash

Aug 25, 2012 15:10

yes

Clash

Aug 25, 2012 15:07

i have the same result of the determinant of the two 3x3 matrixes on my notepad

Clash

Aug 25, 2012 15:06

so, I have this 4x4 matrix and I want to calculate it's determinant, I have typed everything in wolfram alpha: http://www.wolframalpha.com/input/?i=det%5B%7B%7B1-X%2C0%2C0%2C1%7D%2C%7B0%2C-1-X%2C-1%2C0%7D%2C%7B-1%2C0%2C-X%2C-1%7D%2C%7B0%2C1%2C1%2C-X%7D%7D%5D
the determinant is x^4, which I can't see why. I tried using Laplace on the first line to get two 3x3 matrixes and the result is different, I must be doing something wrong: http://www.wolframalpha.com/input/?i=det%5B%7B%7B0%2C-1-X%2C-1%7D%2C%7B-1%2C0%2C-X%7D%2C%7B0%2C1%2C1%7D%7D%5D*%28-1%29 and http://www.wolframalpha.com/input/?i=det%5…

Clash

Aug 25, 2012 15:04

hey guys, could someone help me calculating the determinant of a matrix?

Clash

Jul 1, 2012 09:17

ok I think I got it the normal way
the derivative of $g(x)$ is $\frac{x}{\sqrt{x^+2}}$, which is always smaller than 1. Then using the mean value theorem, we have
$\frac{g(b)-g(a)}{b-a}=\frac{x}{\sqrt{x^+2}}<1$, which proves what I wanted to show, right? $|g(b)-g(a)|<|b-a|$

Clash

Jul 1, 2012 09:12

oh I think I just need to derivate g and do some stuff, sec.. thanks for the tip!

Clash

Jul 1, 2012 09:11

ok yeah, its the Mittelwertsatz der Differentialrechnung, I (should) know it

Clash

Jul 1, 2012 09:10

sec, let me translate that

Clash

Jul 1, 2012 09:10

I mean, I can show $g(x) > x$ for every $x$, but I guess this doesn't help me either

Clash

Jul 1, 2012 09:09

lol

The Whiteboard

General Discussion for softwareengineering.stackexchange.com P...

Clash

Oct 14, 2013 09:39

@WorldEngineer thank you and your girlfriend! What do you mean farm out to the Programmers blog? Does that mean I could post it to the programmers blog? That'd be awesome! Tell me what I have to do!

Clash

Oct 13, 2013 15:06

Hey guys, this is my first blog post about programming and I'd very much appreciate any form of feedback! bernardopires.com/2013/10/… Many thanks if advance!