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seen Aug 25 at 23:19

May
14
comment Converting HeavisideTheta[]s and Sign[]s functions to a single Piecewise[]
Done. Actually it's not a quartic strictly speaking, but while solving the equation in order to find the zeroes, you get a quartic and so you get 4 solutions in the end.
May
14
comment Converting HeavisideTheta[]s and Sign[]s functions to a single Piecewise[]
No, they are not. Some of them are quartic, however it's possibile to find the zeroes of each one analytically.
May
14
comment Is Mathematica really getting this limit wrong?
Thank you very much Daniel. Just one additional question: why is everyone saying that the limit should go unevaluated? Isn't Sign[A] a correct result?
Mar
1
comment Non-linear integral equation
@george2079: it should converge, at least it is eq. 5 in this paper: journals.aps.org/prl/pdf/10.1103/PhysRevLett.74.1633 The authors refer to an unpublished paper for the numerical part, commenting as follows: letting $x=tan(\beta)$, we set up a Gaussian-quadrature grid for $\beta$ and convert the above equations into a matrix form which can be solved iteratively. The logarithmic singularities are treated separately.
Feb
28
comment Non-linear integral equation
I edited the question to include some more details! Thank you for your links!
Jul
4
comment MathLink and a function of a real variable
Thank you! Accepted!
Jul
4
comment MathLink and a function of a real variable
That's what I need, I thought that N[integer] would remain an integer, but this is not the case. If you want to convert your comment into an answer I will accept it. Thank you!
Nov
5
comment Interpolating a function of two variables
chris: works like a charm! Too bad it's only a comment and I can't accept it... :-)
May
22
comment Finding ranges of a parameter for which a function is always positive
That's exactly what I was looking for! Thank you!
Apr
17
comment Coulomb potential as a Fourier transform
I can't reproduce the result, if I copy your code and paste it into a new Mathematica workbook I get: -(Sinh[m r]/(4 [Pi] r)) however, this is clearly the way to go! :-) Answer accepted!
Apr
17
comment Coulomb potential as a Fourier transform
I'm fine with the logs, but the EulerGamma is completely unexpected!
Apr
17
comment Coulomb potential as a Fourier transform
@F'x In 2D it fails to evaluate the output with the mass term. In 3D it gets stuck for ages thinking and then gives the input as output (not able to solve it, I suppose). I remember that in 2D the mass is not needed for convergence, so I've tried and the output is: 1/2 (-HeavisideTheta[-x] (2 EulerGamma + Log[-x - I y] + Log[-x + I y]) - HeavisideTheta[x] (2 EulerGamma + Log[x - I y] + Log[x + I y])) while I was expecting: $k \ln(r)$