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tush
tush
00:16
@Nasser thanks. But Position[l, _?Negative] does give a result. Only when adding the && EvenQ does it not work. I don't understand why
 
3 hours later…
kirma
kirma
02:47
@tush That's because _?Negative form expects the stuff after ? to be a function. You can do Position[{1, 2, 3, -2}, x_?(Negative[#] && EvenQ[#] &)]
 
2 hours later…
kirma
kirma
04:32
user image
Nice automatic layout for less obvious graph...
 
2 hours later…
kirma
kirma
06:40
The sad part is though that a nice planar layout would be plausible, but not really offered by Mathematica...
Chris K
Chris K
07:08
Three-word horror story contest:
"Formatting notebook contents"
4
kirma
kirma
@ChrisK I also accidentally did DiscretizeRegion instead of BoundaryDiscretizeRegion with a small MaxCellMeasure and watched how process sizes went up and down from tens to hundreds of gigabytes for quite a while... I think it was during "Formatting notebook contents." Of course the last saved version of the notebook was several hours old at that point.
Not exactly a horror story, but it also took some head-scratching recently when Graphs seemed to be missing edges... because Select just silently ignores non-Boolean results (from a symbolic RegionMember)...
Because comparing complicated numeric constants is hard.
 
4 hours later…
rhermans
rhermans
10:52
@ChrisK Probably it would be desirable to have a default MemoryConstrained and TimeConstrained like when in Wolfram Cloud with a limited account. Most of the time I use large memory or time is because I did something wrong.
kirma
kirma
11:39
@rhermans Yeah, at least on the user interface side.
rhermans
rhermans
12:33
@kirma Let's do it.
hana
hana
12:47
Can you do this using pure function?
MapThread[(Plus[#1, #] & /@ #2) &, {Range[
3], {{a, b, c}, {d, e, f}, {g, h, k}}}]
The expect result is {{1 + a, 1 + b, 1 + c}, {2 + d, 2 + e, 2 + f}, {3 + g, 3 + h, 3 + k}}.
I know that I can defind this but it's not pure function.
plusMap[x_, y_] := Plus[x, #] & /@ y
MapThread[
plusMap[#1, #2] &, {Range[3], {{a, b, c}, {d, e, f}, {g, h, k}}}]
kirma
kirma
13:08
@rhermans I'm not sure if "we" can do it... :I Might require co-operation from WRI.
rhermans
rhermans
13:45
@kirma I can't remember now the name, but wasn't there a function that get evaluated every time we evaluate a cell? Can't we define a "safe-mode" wrapper for all evaluations?
Found it, it's called $Pre.
rhermans
rhermans
13:57
ClearAll[safeModeWrapper];
SetAttributes[safeModeWrapper, HoldAll];
safeModeWrapper[expr_] := MemoryConstrained[TimeConstrained[expr,3],10^4]
$Pre = safeModeWrapper;
But it seems like this looks like calling for further problems...
kirma
kirma
@rhermans It's not really uncommon to have tens of gigabytes of stuff as a result from a computation, but if it ends up being processed by the front end that's a problem...
Domen
Domen
14:40
@bmf Replying to your statement about answering in the comment (mathematica.stackexchange.com/questions/279937/…): Usually, I don't know what to do in such cases. I consider questions which can be answered by using one single Mathematica command as either "easily found in documentation" or "duplicates" – which this one clearly is. That is why I usually leave a comment before flagging the question.
bmf
bmf
15:10
@Domen so, first of all thanks for taking the time to write to me. I deleted this comments from my answer because I did not want it to seem as a personal attack. I left a similar comment under another section quite recently. Anyway, all is well and we all have our opinions. It's true that perhaps one-liners are too trivial.
I just see a lot of answers being presented in the comments section. Anyway, whatever makes any of us happy
rhermans
rhermans
16:02
@kirma The code and constraints I quote here are just for testing, and yes, I hope there is a way to define $Pre only for the front-end. Is there? I don't claim this code is a robust solution, I know it is not. I'm sharing as a prompt to improve the idea.
kirma
kirma
16:58
@rhermans Thanks for the idea :)
Mats Granvik
Mats Granvik
17:50
If I type something like this into Mathematica:

(*start*)
Clear[s, A, B, n, z, k];
n = 19;
Reduce[rho == s + 1/n + 1/(1 - A/B) &&
s + 1/n + 1/(1 - A/B) == Conjugate[-s - 1/n + 1/(1 - B/A)] &&
B != 0, Re[rho]]
(*end*)

Is the resulting output equivalent to the statements in the program or is it a oneway implication?
I am not strong in logic, and any hints are welcome.
 
2 hours later…
Vinicius Holmes
Vinicius Holmes
20:11
To whom it may concern.
Hello, my name is Vinicius, and I need the help of Mathematica & Wolfram Language.
Last year, the users @Michael E2 and @cvgmt presented valuable suggestions and orientations that have greatly helped me with my research problems. Today, I am writing a scientific work in which I want to acknowledge these users, but I am facing difficulties in contacting them (Below, you may find the links to my posts).

Bearing this in mind, is there any way to contact these users from Mathematica & Wolfram language?

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