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What is in your Mathematica tool bag? [closed]
...ned this before, but the tool I find most useful is an application of Reap and Sow which mimics/extends the behavior of GatherBy:
SelectEquivalents[x_List,f_:Identity, g_:Identity, h_:(#2&)]:=
Reap[Sow[g[#],{f[#]}]&/@x, _, h][[2]];
This allows me to group lists by any criteria and tran...
Can a class member function template be virtual?
...would need to call a templatized virtual function, compilation is all done and the compiler cannot generate the appropriate instance anymore. Therefore you cannot have virtual member function templates.
However, there are a few powerful and interesting techniques stemming from combining polymorphi...
Abusing the algebra of algebraic data types - why does this work?
...ely, all unit types. They behave identically under algebraic manipulations and, more importantly, the amount of information present is still preserved.
You probably want a zero type as well. Haskell provides that as Void. There are no values whose type is zero, just as there is one value whose type ...
Is Redis just a cache?
I have been reading some Redis docs and trying the tutorial at http://try.redis-db.com/ . So far, I can't see any difference between Redis and caching technologies like Velocity or the Enterprise Library Caching Framework
...
Understanding slice notation
...t value that is not in the selected slice. So, the difference between stop and start is the number of elements selected (if step is 1, the default).
The other feature is that start or stop may be a negative number, which means it counts from the end of the array instead of the beginning. So:
a[-1]...
Why does this Java program terminate despite that apparently it shouldn't (and didn't)?
...etely wrong. An actuator on an electron microscope went over its boundary, and after a chain of events I lost $12 million of equipment. I've narrowed down over 40K lines in the faulty module to this:
...
Why not use Double or Float to represent currency?
...lways been told never to represent money with double or float types, and this time I pose the question to you: why?
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How do I select elements of an array given condition?
...e elements in y corresponding to elements in x that are greater than 1 and less than 5.
6 Answers
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Delete all data in SQL Server database
...e all records from all tables of my database? Can I do it with one SQL command or I need for one SQL command per one table?
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Explain the use of a bit vector for determining if all characters are unique
...ay be a little bit faster, because operations with bits are very low level and can be executed as-is by CPU. BitVector allows writing a little bit less cryptic code instead plus it can store more flags.
For future reference: bit vector is also known as bitSet or bitArray. Here are some links to thi...