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Oct
14
comment compile function and floating points
@OleksandrR. I see your point (I was just experimentally looking for a small enough number so to my shame did not even know what MachineEpsilon is supposed to be). How do you feel about x = 1. + 0.001 $MachineEpsilon;x - 1 as an example, then?
Oct
14
comment compile function and floating points
@OleksandrR. I don't understand what you're saying I'm afraid. Can you unpack this a bit? (also, any thoughts on this?)
Oct
14
revised Speeding up construction of simple tridiagonal matrix
added 165 characters in body
Oct
14
answered compile function and floating points
Oct
13
comment Speeding up construction of simple tridiagonal matrix
Maybe part of the speed difference is related to unpacking? Also, it appears that how faster this is (faster than Band) depends on the system size--see update in my question. I wonder why.
Oct
13
revised Speeding up construction of simple tridiagonal matrix
Added speed comparison and mention of packing
Oct
13
asked Speeding up construction of simple tridiagonal matrix
Oct
12
awarded  Nice Answer
Oct
12
revised Custom File Palette
added 390 characters in body
Oct
12
comment Custom File Palette
@cormullion you're right, if you want only nb and m files to appear. originally this was part of a palette I have where each file is treated differently according to extension (basically a way for me to avoid having to leave mathematica to manage my output files etc)
Oct
12
answered Custom File Palette
Oct
12
comment How often does Mathematica contact its license server?
While I have no definitive answer (nor can I capture traffic on my work machine to check), I know from experience that if the license server goes down, mma does not close. I've had it run for a couple of hours, finish the task, and exit, while the license server was dead (according to IT support). So, unless it was somehow coming online briefly, it seems that this puts a lower bound on the period with which it checks.
Oct
11
comment How to sum up large number of elements in a table quickly?
this (how to speed it up) might depend on the details. unpacking might be involved for instance. Could you post some code that produces a1 and a2 in the form you need them, then uses f the way you use it?
Oct
11
comment How to sum up large number of elements in a table quickly?
@user72409 sorry I botched the pasting and did not actually paste the faster version. In any case I don't know if this will remain faster for such large arrays (and it needs modification to work with 2D arrays anyway; perhaps you could mention this in your question!)
Oct
11
revised How to sum up large number of elements in a table quickly?
mentioned unpacking
Oct
11
comment How to sum up large number of elements in a table quickly?
@tkott evaluate SetSystemOptions[PackedArrayOptions->UnpackMessage->True] and you'll see :)
Oct
11
revised How to sum up large number of elements in a table quickly?
added 56 characters in body
Oct
11
answered How to sum up large number of elements in a table quickly?
Oct
11
revised NDSolve with Euler method
added 32 characters in body
Oct
11
comment Eigenvalue / Eigenvector Calculation
"For speeding up Mathematica code, a little analysis of a problem often goes a long way" an excellent point. +1 for that and +1 for the rest (if I could)