================================== Top new questions this week: ==================================
[How to implement a discrete data representation?] http://mathematica.stackexchange.com/questions/139818/how-to-implement-a-discrete-data-representation
I’m currently working with large datasets of "discrete data". Each of these is a multiset of real numbers of the form \(kS + B\), where \(k\) is an integer, and \(S\) (the "scale") and \(B\) (the "bias") are ...
- asked by kjo (17 votes), answered by gwr (14 votes)
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[Mathematica incorrectly giving zero for partial derivative] http://mathematica.stackexchange.com/questions/139669/mathematica-incorrectly-giving-zero-for-partial-derivative
Bug introduced in 9.0.1 or earlier
Mathematica is incorrectly reporting that the partial derivative of a certain expression is zero.
I try to compute the following:
D[SymmetricPolynomial[3, {x1, ...
- asked by Izaak Meckler (17 votes), answered by march (6 votes)
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[Finding vampire numbers] http://mathematica.stackexchange.com/questions/139808/finding-vampire-numbers
How to find vampire numbers by using Mathematica?
A number \(v=xy\) with an even number \(n\) of digits formed by multiplying a pair of \(n/2\)-digit numbers (where the digits are taken from the ...
- asked by vito (13 votes), answered by wolfies (8 votes)
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[Why do subsequent evaluations seem to be stopped by a False Condition (/;)?] http://mathematica.stackexchange.com/questions/139461/why-do-subsequent-evaluations-seem-to-be-stopped-by-a-false-condition
Exploring another problem and this example of @halirutan, I came across an evaluation behavior I don’t understand.
When g[] below is evaluated the first time, ig[] is evaluated and a message printed; ...
- asked by Michael E2 (12 votes), answered by Carl Woll (13 votes)
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[Bug? Numerical calculation error with FullSimplify and arbitrary precision] http://mathematica.stackexchange.com/questions/139697/bug-numerical-calculation-error-with-fullsimplify-and-arbitrary-precision
Bug introduced after 5.2, fixed in 8.0, reintroduced in 9.0 and persisting through 11.0.1
Is this a bug?
If I do
FullSimplify[n E^(0``10 n)] then it returns n/2
what is obviously incorrect.
...
- asked by David Bevan (10 votes)
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[Is there a convention on which name to use for a throwaway variable? (Like underscore in Python)] http://mathematica.stackexchange.com/questions/139622/is-there-a-convention-on-which-name-to-use-for-a-throwaway-variable-like-under
I would prefer to write {_, foo} = LongFunctionName[arg1, arg2] instead of foo = LongFunctionName[arg1, arg2][[2]] or foo = Last @ LongFunctionName[arg1, arg2]. Using an actual name for the throwaway ...
- asked by ZeitPolizei (10 votes), answered by Mr.Wizard (5 votes)
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[Extract images from large avi movies (50-100 GB)] http://mathematica.stackexchange.com/questions/139819/extract-images-from-large-avi-movies-50-100-gb
I will get large RGB avi files (35 Hz, 1600*1200 pixels) of up to 100 GB size. All three channels contain the same grayscale image.
I want to extract each avi file into one channel png images.
To do ...
- asked by mrz (8 votes), answered by mrz (11 votes)
================================== Greatest hits from previous weeks: ==================================
[How to tell Mathematica that certain variables are real/imaginary, integer-valued, etc] http://mathematica.stackexchange.com/questions/66273/how-to-tell-mathematica-that-certain-variables-are-real-imaginary-integer-value
I’m trying to expedite some quantum mechanical calculations by running them through Mathematica. Expectation values and stuff like that. When I say, for example,
u[x_] := Sqrt[2/L] * Sin[Pi * n * x / ...
- asked by Matthew Brunetti (11 votes), answered by SquareOne (9 votes)
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[Where can I find examples of good Mathematica programming practice?] http://mathematica.stackexchange.com/questions/18/where-can-i-find-examples-of-good-mathematica-programming-practice
I consider myself a pretty good Mathematica programmer, but I’m always looking out for ways to either improve my way of doing things in Mathematica, or to see if there’s something nifty that I haven’t ...
- asked by J. M. (460 votes), answered by faysou (404 votes)
================================== Can you answer these? ==================================
[Integrating rational functions of several variables over \(\mathbb {H}^4\)] http://mathematica.stackexchange.com/questions/139631/integrating-rational-functions-of-several-variables-over-mathbbh4
Let \(W\) be a rational function of \(8\) variables \(a,b,c,d,e,f,g,h\) from this file, e.g.:
W = (256*b*d*f*(a^5 + b^4*(c - 2*e) - a^4*(3*c + 2*e) - c*(c^2 + d^2)*(e^2 + f^2) + a^3*(2*b^2 + 3*c^2 + d^2 + ...
- asked by Ricardo Buring (4 votes)
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[Best Wolfram tool for interactive web-based calculator] http://mathematica.stackexchange.com/questions/139954/best-wolfram-tool-for-interactive-web-based-calculator
A colleague is considering re-implementing this online "Photon Propulsion Calculator" using a Mathematica-based product. I wanted to ask the community which product would be best.
WebMathematica
...
- asked by ConvexMartian (8 votes)
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[How to get rid of a built-in context from autocomplete?] http://mathematica.stackexchange.com/questions/139783/how-to-get-rid-of-a-built-in-context-from-autocomplete
I have noticed that when I type the name of built-in function Limit in Mathematica, the autocomplete suggests two variants at the top: the first one is the working one, and the second one is just ...
- asked by user372003 (4 votes)