Mathematica

Hilbert Transform
Has an efficient Hilbert Transform or Discrete Hilbert Transform been implemented in Mathematica? I can code my own, but my implementations tend to be ham-handed and not too efficient. Daniel ... 6 Feb 2010 04:15

Bug? Analytical integration of cosines gets the sign
On Thu, Feb 4, 2010 at 6:32 AM, K <kgspga(a)googlemail.com> wrote: faultyInt = Integrate[Cos[ph]*1/Pi*Cos[4*ph]*Cos[2*ph], {ph, Pi, 3/2*Pi}] gives as result: 19/(105 \[Pi]) Yes, I'd agree that's a bug. It does not occur in V6.0 or V5.2. Also, if you pass the integrand to TrigExpand, you will find that y... 5 Feb 2010 03:56

Sort of nested NIntegrate
I have the following little problem with a function defined by means of NIntegrate. My function is much more complicated, but the following example suffices. Suppose I've defined a function in this way fu[x_] := NIntegrate[ Cos[ x * Sin[t] ], {t, 0, 1}]; Mathematica can easily compute numerically and plot th... 5 Feb 2010 08:17

NonlinearModelFit vector valued functions
NonlinearModelFit is able to fit to a scalar valued function, including complex valued functions. However, I would like to fit to a vector valued function. I can do this using NMinimize, but in that case I'll lose all the nice statistics NonlinearModelFit provides us. Any idea to circumvent this problem? Tha... 4 Feb 2010 06:39

intersecting surfaces
Hello Guys, How to set CountourPlot3D to plot the intersection of two surfaces. For example I would like to see the curve of the intersection of these cones: ContourPlot3D[{((x - 1)^2 + (y)^2) Cos[Pi/4]^2 - ((z ) Sin[Pi/4])^2 == 0 , 0 == (x^2 + y^2) Cos[Pi/6]^2 - (z Sin[Pi/6])^2}, {x, -5, 6}, {y, -5, ... 5 Feb 2010 03:56

DeleteDuplicates is too slow?
Hello, Suppose you have the following. Data = RandomReal[1,{N,2}]; sameQ[_,_]=False; sameQ[{x_,y_},{x_,z_}]=True; Timing[DeleteDuplicates[data,sameQ]][[1]]; If N is a large number this takes an ungodly amount of time? Is there a more efficient way to delete the duplicate entries of Data ? ie. D... 7 Feb 2010 06:29

Diagonalizing large matrices
Hi guys I am in a situation, where I have to diagonalize very large matrices. My experience with Mathematica is limited, but what I need is the entire set of eigenvalues. From what I have read, this excludes the use of ARPACK, since this is used to find certain eigenvalues (i.e. largest, smallest etc.). I rea... 13 Feb 2010 06:02

Normality test
Hi. I wonder if anybody knows a function similar to qqnorm(data) from *R*, producing a normal scores plot, or some related tools in M. for testing normality of data? Thanks Michael Partenskii ... 15 Feb 2010 06:30

Can Mathematica solve this differential equation ?
In beam bending, we have the following situation: y '' [x] = M(x), boundary conditions specified for y[0] and y[1] Simple enough, but the problem arises as M is a piecewise-defined function (linear in all pieces though) i.e., M(x) = M1(x) for 0<x<1 and M(x) = M2(x) for 1<x<2 M(x) = 0 for all other values... 3 Feb 2010 07:14

Conjecture:at least one prime p between (n-1)n/2 and n(n+1)/2
I have a Conjecture: For every n > 1 there is always at least one prime p such that (n-1)n/2 < p < n(n+1)/2 n = 2; b = 1; While[NextPrime[b] < (b = n (n + 1)/2), n++] n $Aborted 14394105 In this diagram,there is at least one small point(prime) between every two medium points(triangle number ). In... 3 Feb 2010 07:14