Wolfram Mathematica

acl

12:00 AM

@hwlau right L3

hwlau

the cache in AMD works more "separately" than intel

acl

well either way, I'll check tomorrow. But this seems to be happening at too high level to be that. But who knows

@hwlau well I have no idea, I don't really know much about physical layer stuff :)

hwlau

But this physical layer really affect the performance

acl

@hwlau Yes I understand. But there is an infinite number of things to wonder about, and one has to be selective

hwlau

@acl Ya, the mathematica also add a layer there, so it is not transparent. I don't usually have problem when I write C++ program.

But the scaling of large system should always correct, so there is no problem of estimation.

acl

12:07 AM

@hwlau Neither do I in terms of performance (usually), but I consider writing C a problem :)

@hwlau OK I don't disagree of course. That's the main problem with mma, scaling things up needs experience (and may not be possible)

hwlau

@acl BTW, is it easy to pass vectors and matrices to a manually compiled C code program, and return them back?

acl

@hwlau reasonably, although I don't have as much experience as eg szabolcs and halirutan on this (I just played with it, wrote one piece of code and then just use that since)

Mr.Wizard

@acl I posted this:

1

Q: Menu bars on Palette windows don't work properly -- any workarounds?

After getting help from Rojo with Menu commands on Palettes and other windows without menu bars? I was able to create a Palette with a menu bar by: Selecting the Palette and opening the Option Inspector with Ctrl+Shift+O Setting Editable -> True and WindowElements -> {"MenuBar"} However the b...

acl

@Mr.Wizard Yep, that is what I had in mind

Mr.Wizard

The real conundrum for me is how one is supposed to easily edit a Palette as I can't figure out how to use Generate Notebook from Palette in v10. (Windows.) Have you figured that part out?

acl

12:18 AM

In any case for now I use Notebooks[] etc

hwlau

@acl How much are the different between the generated C codes from mathematica, and manually written C code?

acl

@Mr.Wizard it does seem to work, but as I have never used it before, I don't know what it's supposed to do. it literally generates a notebook with the buttons in it (and FullForm works on them)

@hwlau hm, hard to say, but you can look for yourself at the generated C code (it's explained in the docs)

@hwlau paste this into the doc centre

Compile/tutorial/CompilationTarget#613519836

Mr.Wizard

@acl If you've never used it before there must be another approach that I am somehow blind to. If you have a palette that you wish to modify and save, possibly as a copy, how do you do it?

acl

@Mr.Wizard I never modify my palettes. I have notebooks which produce them, and modify those, then save the resulting palette

I didn't even know you could modify an existing palette until you mentioned it just now...

@hwlau search for Inspecting Generated Code

Mr.Wizard

@acl Do you not have the Generate Notebook from Palette menu command?

acl

12:25 AM

@Mr.Wizard I do. I just noticed it now that you mentioned it. I never use menus if I can avoid it, so had not noticed it.

hwlau

The codes can be understood in my eye. They are splitted into so many piece.

acl

@Mr.Wizard What it does here is this: for a palette with 3 buttons, it produces a nb with the three buttons. FullForm works ok on them

hwlau

Also the generated codes doesn't seem to allow some flags

compile flags

acl

@hwlau it's not really meant to be human readable I guess

Mr.Wizard

@acl Die-hard old-school? Keyboard shortcuts over mouse I take it? I admit that is faster for those who master it.

hwlau

12:28 AM

@Mr.Wizard yes, die hard

acl

@Mr.Wizard OS X is nice in this regard. You can assign system-wide shortcuts, assign key board shortcuts to arbitrary menu entries in any application, etc

Mr.Wizard

@acl What OS are you using and when is that command active? Or perhaps I should say where since there is no menu bar on a palette?

acl

also, the basic emacs keyboard navigation shortcuts work pretty much everywhere

@Mr.Wizard This is on OS X, where the menubar of the active application is always at the top of the screen, not attached to any particular window

Mr.Wizard

It does sound easier under that OS (which you just answered). Perhaps some day I'll rise to that level of proficiency in Mathematica.

Rojo

@acl I want that

Mr.Wizard

12:30 AM

@acl Okay. It's got to be a Windows problem then. Thanks.

acl

@Rojo stick to your vim

Rojo

@acl I meant the OSX thing

You can keep your emacs

acl

@Rojo hmm, turns out vim comes installed with os x (I use emacs so hadn't noticed). so now I started it

how do I get out?

(seriously)

ah! never mind

Rojo

@acl Unplug the PC

hwlau

@Rojo +1

acl

12:32 AM

@Rojo :q

I'll print it and put it on my office wall just in case

hwlau

@acl don't just click the cross :)

acl

@hwlau what cross?

hwlau

@acl close the windows

acl

@hwlau ah

hwlau

It is not the right way to get out, not much better than unplug :)

acl

12:37 AM

@hwlau depends. there is some satisfaction in extinguishing the life out of a vim instance

hwlau

@acl I think most people do the same thing they enter vim for the first time

acl

@hwlau it's not terribly intuitive.

halirutan

3:22 AM

Hello all. Is it only me on Linux or is it no longer possible to copy&past cells from one notebook to the other without loosing the cell structure??

Rojo

3:44 AM

@halirutan I just copied and pasted a cell properly. Do you have an example?

@halirutan By the way, my f%%2#$% $MachineID changes some times with the Linux kernel updates, which is %#$% annoying. Did that ever happen to you?

halirutan

@Rojo No. Never.

@Rojo Aehm.. It doesn't happen right now but it happened some minutes ago.

Rojo

@halirutan Oh, ok. I just had to boot with an older kernel to have mma active

halirutan

@Rojo This should not happen. Didn't happen for me. I would definitely complain about that at Wolfram because the kernel updates every few weeks for me.

Rojo

@halirutan Yes. 2 licenses. I can't use the same on Linux and Windows on the same machine. At least I ask to be able to not need both for just one Linux, hehe

mfvonh

4:38 AM

@halirutan I have been having all sorts of difficulties with copy/paste on Windows

It's pretty annoying

halirutan

@mfvonh Me too on Linux. When I use the normal Google Chrome and I copy code from Mathematica to Chrome, I get additional bytes.

This is the cell I want to copy

and this is what arrives in Chrome

Pretty neat. Now I have to use Chromium to circumvent this.

mfvonh

@halirutan Weird. That one works fine for me. I have been getting frustrating behavior where sometimes it gives me box structures when I copy an expression that shouldn't have them (like just a list or something). But it's not consistent. I'm having to do Copy As -> Plain Text a lot

And then sometimes when I copy it will try to turn the notebook into a template notebook, or it will open a new testing notebook. And then sometimes when that happens Ctrl + C will get hooked to creating a new testing notebook.

I have to shut MMA down entirely

I only started using MMA in v9 so I haven't been through an upgrade before. I guess it is weird to encounter several rough patches all at the same time in a system I like so much

halirutan

5:08 AM

@mfvonh For this you can use Ctrl+Shift+C, so you don't need the mouse.

(Basically, I always use Ctrl+Shift+C when I want to paste something to a post or here into chat)

acl

9:44 AM

8

A: Schroedinger eigenvalue problem in two dimensions (Harmonic Oscillator)

In order to give one possible answer, I'll just take the isotropic harmonic oscillator in 2D and do a finite-difference calculation by discretizing the xy plane with constant spacing a. Here is the construction of the resulting matrix for the Hamiltonian, h. I assume the origin of our spatial g...

Jens' answer deserved many more upvotes... But it's probably hard to appreciate it without knowledge of the problem he's solving

Many more upvotes, in fact.

I mean it has as many upvotes as straightforward applications of MapThread I've posted. Come on.

acl

10:06 AM

A quick question: Suppose I want to set up InputAutoreplacements for some notebook, and do it like this:

SetOptions[SelectedNotebook[],
 InputAutoReplacements -> {"url" ->
    "Hyperlink[\[SelectionPlaceholder],\[SelectionPlaceholder]]"}]

what this does is let me type url and have auto-expand, placing the cursor in the first argument of Hyperlink. This way I can type a label, tab into the next argument and type the url

now, what if I wanted to have an actual label appear instead of the filled square? How could I do that?

I mean like the front end does here:

this must be simple

Or does nobody actually use this stuff?

Rojo

1:33 PM

@acl Hello

It looks like the boxes are TagBox[ FrameBox["theLabel"], "Placeholder"]

sooo

Nasser

when solving a differential equation using DSolve with no initial conditions, should not the answer always contain a constant of integration?

Rojo

SetOptions[SelectedNotebook[],
InputAutoReplacements -> {"url" ->
RowBox[{"Hyperlink", "[",
RowBox[{"\[SelectionPlaceholder]", ",", TagBox[
FrameBox["label"],
"Placeholder"] }], "]"}]}]

acl

@Nasser ideally

@Rojo thanks

@Rojo fantastic! thanks.

Nasser

@acl humm... so if DSolve returns an answer without C[1], is this a bug or not?

belisarius

:16655081 You've got no answers to your transvestite-cursor question. You should learn to sing.

Nasser

1:37 PM

For a first oder differential equation..

acl

@Nasser I suppose. what's the equation?

Nasser

@acl, good. so I can post it on main board. Here it is:

DSolve[D[y[x], x] - y[x]^2 + y[x]*Sin[x] - Cos[x] == 0, y[x], x]

I'd like to know why M does not return C[1]

Rojo

@belisarius I will wait another couple of years before I give up on that answre

Nasser

Isn't solution without C[1] a particular solution? and the answer should be general solution?

belisarius

@Rojo I tried that on my machine and it works.

acl

1:45 PM

@Nasser I don't have any experience with DSolve but yes you're right, there is a constant missing

Rojo

@belisarius What, the waiting or the suggestion by mwnwwmw on the comments?

belisarius

@Rojo Regretfully I can't copy my singing as an answer

Nasser

@acl thanks for your input. Will post it on main board to give chance for someone to see why it is missing in this case.

Rojo

@belisarius You can

belisarius

@Rojo I still have a little drop of decency remaining.I won't.

Rojo

1:49 PM

@belisarius I'll ask again in a few months then

Mr.Wizard

@mfvonh I am happy to answer questions about my answers and methods. Don't hesitate to ask, unless you learn better by working through it alone.

Rojo

@Mr.Wizard Wizard, about that step thing. I haven't posted another approach because I think perhaps it isn't useful given yours

Meaning, yours advances one step, either argument evaluation, changes because of attributes, or iteration. What goes straight to the next iteration

Mr.Wizard

@Rojo Do you care to post it here in chat? I'm interested. What was your target application and behavior?

Rojo

@Mr.Wizard Not much, I think I did it when that question was posted, then didn't feel lke posting it OR didn't have the time to try and fix all the possible errors that might come out from people inspecting it, so I didn't.

@Mr.Wizard 1 sec, I'll paste it here

Nasser

I'll no longer will help in formatting user's code, it is waste of time. Today I did this for someone, then few minutes later they updated the question, erasing all the edits I did when they reposted the code again :)

3

Mr.Wizard

2:05 PM

@Nasser That's your prerogative. I am inclined to roll back the edit when that happens and ask the OP to try again, this time respecting the formatting. I think I've only done that once or twice however.

Rojo

@Mr.Wizard Sorry, work stuff. Back. This is what I've been using (barely)

SetAttributes[{Step, stepIterative, stepTrace}, HoldAllComplete];
Options[Step] = {"Attributes" -> False};
Default[Step, 2] = HoldComplete;
Step[code_, (wrapper : Except[_?OptionQ]) // Optional,
   OptionsPattern[]] :=
    stepTrace[code, wrapper] /; OptionValue["Attributes"];
Step[code_, wrapper : Except[_?OptionQ] // Optional,
   OptionsPattern[]] :=
    stepIterative[code, wrapper];

(* MrWizard *) (* Ojo que así como está aplica el wrapper cuando no \
hubo iteraciones *)
stepTrace[expr_, wrapper_] :=

@Mr.Wizard That goes to your version when the option "Attributes" is set to True, and by default to mine. Mine just uses $IterationLimit

to force it to stop after one iteration

(there was an extra Print. Corrected)

f[x_] := g[2 + 3];
g[x_] := x^3;
Step[f[2 (3 + 4)]] gives HoldComplete[g[2 + 3]]. Yours gives HoldComplete@f[14] as a first step

As it is, HoldComplete is the default wrapper. You can put any wrapper as second arg

Mr.Wizard

@Rojo Thanks. I'll enjoy looking at that later. Apparently I'm too tired right now as it's not making sense. :^)

Rojo

@Mr.Wizard It just sets IterationLimit low, iterates needlessly a few times, and then runs the code,w hich is stopped because it hits the limit

Mr.Wizard

Okay, that makes sense I guess, but I never considered such a thing. See, I'm glad you shared this. :-)

Rojo

@Mr.Wizard :)

A nice wrapper (2nd arg) could be something like this. Function[Null, Interpretation[HoldForm@#, Step[#, #0]], HoldAll]

that lets you evaluate the output time and time again to get the next step

Mr.Wizard

2:15 PM

@Rojo That sounds similar to this:

If you change the return value from # to # /. HoldForm[x_] :> Defer[step[x]], then the resulting expression is in a convenient form for further stepping. One can repeatedly type SHIFT-CONTROL-L, SHIFT-ENTER to step through the surface evaluations until the expression goes inert. — WReach Feb 8 '12 at 14:10

Rojo

@Mr.Wizard Exactlyyyy

Mr.Wizard

One more thing to play with. I do need to go however. It's been a long time since we chatted; I should do something about that.

Rojo

@Mr.Wizard :) We'll talk soon

Mr.Wizard

Good. :-)

mfvonh

2:28 PM

@Mr.Wizard Thank you :) I knew I could ask, I was just trying to figure out what I wanted to ask. Which is: I thought ought to be able to nest more P = corresponding to the TraceDepth setting (so I could go deeper, assuming for now the expression is complex enough), but that does not seem to be the case.

Or maybe I am not implementing it correctly

step2[expr_]:=Module[{P},P=(P=(P=Return[#,TraceScan]&)&)&;
TraceScan[P,expr,TraceDepth->2]]

I don't actually need that functionality. I was mainly testing to see whether I understood how it worked.

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