Math

Derivative of a Fourier transform
Hello All, let function f belong to $L_2(R)$. Let's consider its Fourier transform (as function from $L_2(R)$) $\hat f$. How do we define derivative $(\hat f)'(x)$ (taking into account that $\hat f$ is actually a class of functions that coincide a.e.)? Maybe someone can give a reference to a book whe... 14 Jun 2010 14:01

confidence interval
I have a two sets of N paired real numbers, P=predictions O=observed values I am computing the "average prediction error" as ape=sum(abs(P_i - O_i)) / sum(abs(O_i)), 1<=i<=N How can I calculate a confidence interval on ape? Thanks a lot! Lorenzo ... 14 Jun 2010 07:20

Group theory, semidirect products
Hi, I know the following definition for semi direct products: Let H and N be groups, f : H -> Aut(N) a homomorphism. Then the cartesian product HxN with the multiplication (h,n) * (h', n') := (h*h', f(h'^(-1))(n)*n') (horrible to look at, I know..) forms a group, called semi direct product. Now, as a special c... 14 Jun 2010 15:08

Yeah fame is weird
"JSH" <jstevh(a)gmail.com> wrote in message news:a41adb75-3d12-415e-8d30-904187397ec4(a)k17g2000pro.googlegroups.com... About a decade or so ago some poster noted in reply to me that I was famous and I replied back that no, You're a blithering fuckwit. ... 16 Jun 2010 19:57

JSH: Yeah fame is weird
About a decade or so ago some poster noted in reply to me that I was famous and I replied back that no, I'm infamous. But I guess it really is about how you define "fame" and everybody seems to have their own personal definition. But, I am read in somewhere around 120 countries that I can verify just by hits to... 18 Jun 2010 05:53

Decent ODE book with some solved exercises?
Looking for a good book about ODEs and for mathematicians, if possible (meaning not a book that just tells you the stupid formula and then 50 exercises to use it). Links to webpages with course materials of some professor are also appreciated. Thanks. ... 13 Jun 2010 13:49

How to simplify sum
On Jun 13, 8:26 am, leox <leonid...(a)gmail.com> wrote: How  to simplify to a rational function the following sum \sum x^i y^j z^{a*i+b*j-2k} where a,b integers >0 and i,j,k>=0   run over the set a*i+b*j-2*k>=0? Consider 4 cases: a even, b odd; a odd, b odd; ..... Solve each case separately. ... 13 Jun 2010 11:34

where can i find math school programs for UK or USA?
Hi all! A student is conducting with me a research about math school programs (subjects, strucutral organization of courses and realization in various school). Since i don't know how school programs are organized in UK or USA, i ask here i someone can give me some advice on how to find them. thank you for a... 13 Jun 2010 14:56

How to simplify sum
How to simplify to a rational function the following sum \sum x^i y^j z^{a*i+b*j-2k} where a,b integers >0 and i,j,k>=0 run over the set a*i+b*j-2*k>=0? ... 13 Jun 2010 09:22

[] semi-Hamiltonian paths in planar triangulations
> as far as I can see he asked for a finite planar triangulation. the beginning of my sentences are not capitalized because i'm too lazy to do so. Your objection has been discarded as lazy people don't need to be taken seriously. -- For blatantly flaunting deliberate illiteracy, he deserves Capital Puni... 13 Jun 2010 07:12