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by szhorvat
Wed Oct 04, 2017 12:24 pm
Forum: Wolfram Language
Topic: i dont see any point
Replies: 18
Views: 13080

Re: i dont see any point

Take a look at

https://mathematica.stackexchange.com/

and

http://community.wolfram.com/

to see what people use it for. Mathematica is an essential tool for many scientists.
by szhorvat
Fri May 05, 2017 2:03 pm
Forum: Mathematica
Topic: Announcement: igraph interface for Mathematica
Replies: 1
Views: 6259

Re: Announcement: igraph interface for Mathematica

The IGraph/M 0.3.91 prerelease is now available for Raspbian Jessie: https://github.com/szhorvat/IGraphM/releases

Any suggestions or bug reports are most welcome.
by szhorvat
Fri Jun 03, 2016 8:30 am
Forum: Mathematica
Topic: new to Mathematica but have used matlab.
Replies: 2
Views: 9332

Re: new to Mathematica but have used matlab.

FourierTransform is not what you need. That function computes a symbolic transform. You need Fourier instead to use on numerical data.

To generate an array, look up Table. To plot it, or its Fourier transform, use ListPlot. Fourier returns complex quantities, so you'll probably want Abs.
by szhorvat
Thu Apr 21, 2016 1:02 pm
Forum: Mathematica
Topic: PlotPoints does NOT work
Replies: 2
Views: 4736

Re: PlotPoints does NOT work

It does work, but PlotPoints doesn't exactly do what you think. It sets the initial number of points. Mathematica may automatically add additional points adaptively for a better quality plot. MaxRecursion controls the number of refinement steps when adding points. To see all the plot points, use the...
by szhorvat
Sat Mar 05, 2016 7:25 pm
Forum: Mathematica
Topic: Announcement: igraph interface for Mathematica
Replies: 1
Views: 6259

Announcement: igraph interface for Mathematica

IGraph/M version 0.2.0, the igraph interface for Mathematica is released today. It can be downloaded from https://github.com/szhorvat/IGraphM/releases This version comes with Raspberry Pi support. IGraph/M complements Mathematica's graph theory and network analysis functionality with many new functi...
by szhorvat
Sat Feb 07, 2015 3:42 am
Forum: Wolfram Language
Topic: How to Run Tests in Command Line Wolfram
Replies: 4
Views: 6068

Re: How to Run Tests in Command Line Wolfram

This does appear to work now in the latest, 2015 Jan 29 version.
by szhorvat
Sat Feb 07, 2015 3:41 am
Forum: Wolfram Language
Topic: How to create animation?
Replies: 3
Views: 5872

Re: How to create animation?

I would recommend exporting the frames one by one as PNG images, then encoding the video afterwards. Yes, Mathematica can export videos directly, but creating frames separately gives you more control and makes it easy to interrupt or resume the process. I do this even on fast desktops, and I wouldn'...
by szhorvat
Sat Feb 07, 2015 3:31 am
Forum: Wolfram Language
Topic: Mathematic query
Replies: 5
Views: 5635

Re: Mathematic query

All built-in symbols in Mathematica have names starting with a capital letter, no exception. Infinity, Pi, I, E, all of them are capitalized. This makes it easy to avoid conflicts with builtins when you create your own symbols: just use lowercase names for your own ones. Also, all of these names are...
by szhorvat
Sat Feb 07, 2015 3:27 am
Forum: Wolfram Language
Topic: Save plots in Mathematica-Command line
Replies: 1
Views: 4134

Re: Save plots in Mathematica-Command line

Certain operations, such as exporting graphics, require the Mathematica "Front End". The Front End is the program that shows Mathematica's GUI. If you run Mathematica in command line mode, and try to export graphics, it will automatically start up the Front End for you without any visible windows, s...
by szhorvat
Fri Feb 06, 2015 8:40 pm
Forum: Mathematica
Topic: What is the latest Mma version as of 2015 January?
Replies: 3
Views: 2539

Re: What is the latest Mma version as of 2015 January?

Thanks for the responses. This new version came out just a few days after I posted my question.
by szhorvat
Thu Jan 22, 2015 3:50 am
Forum: Mathematica
Topic: What is the latest Mma version as of 2015 January?
Replies: 3
Views: 2539

What is the latest Mma version as of 2015 January?

What is the latest Mathematica version for the Raspberry Pi as of 2015 January? I seem to have the 2014 August 4 version, which has $VersionNumber == 10 and $ReleaseNumber == 0.

Is the equivalent of Mathematica 10.0.2 ($ReleaseNumber == 2) available?
by szhorvat
Tue Jun 17, 2014 9:59 pm
Forum: General discussion
Topic: Power external HDD: safe to connect both to RPi and charger?
Replies: 7
Views: 2041

Re: Power external HDD: safe to connect both to RPi and char

Thank you all for the replies. Is the information I can find about "backpowering" also apply to the situation I described (i.e. using the Y cable with a separate power supply)? Or does it only apply to powered USB hubs?
by szhorvat
Tue Jun 17, 2014 9:57 pm
Forum: General discussion
Topic: Power external HDD: safe to connect both to RPi and charger?
Replies: 7
Views: 2041

Re: Power external HDD: safe to connect both to RPi and char

FTrevorGowen wrote: ** I have yet to find such a hub that costs less than the Pi itself so I prefer to use USB HDD's that can be externally powered w/o the use of a "Y cable".
Thanks for the response. Are you aware of any problems with the 7 port hub mentioned here?
by szhorvat
Tue Jun 17, 2014 2:06 am
Forum: General discussion
Topic: Power external HDD: safe to connect both to RPi and charger?
Replies: 7
Views: 2041

Power external HDD: safe to connect both to RPi and charger?

I have an external hard drive that I would like to connect to the Raspberry Pi. This hard drive has a single USB connector and must be powered through it. It came with a cable that has two USB A type ends to be connected to two USB ports of the same computer, for sufficient power. The Raspbery Pi ca...
by szhorvat
Mon Jun 16, 2014 7:57 pm
Forum: Camera board
Topic: Best way to access camera from C
Replies: 3
Views: 2253

Re: Best way to access camera from C

I've never had the time to write a C library/API. MMAL is the best best for generic code, but it's a bit of a handful, and undocumented - raspistill/vid are in effect the documentation. Avoid OpenMAX. It's a right PITA to use. Not sure how well the community based API's have been doing. So based on...
by szhorvat
Mon Jun 16, 2014 7:23 pm
Forum: Camera board
Topic: Best way to access camera from C
Replies: 3
Views: 2253

Best way to access camera from C

There's an (official?) Python API for accessing the camera, and there's raspistill/raspivid/raspiyuv for command line access. What is the best/recommended way to access the camera from C (or C++)? My priority is ease of learning, which means that I prefer well documented complex stuff to udocumented...
by szhorvat
Wed Jun 11, 2014 2:40 pm
Forum: Camera board
Topic: Exposure control goes into oscillation during video recordin
Replies: 8
Views: 2116

Re: Exposure control goes into oscillation during video reco

The code is closed source I am afraid. And horribly complicated (tuning files are about 70k lines long). Low framerate is interesting. How low? Do you get the same at normal framerates? I'll ask around to see if that might cause oscillations. Have you tried different exposure modes or fixed gains? ...
by szhorvat
Wed Jun 11, 2014 2:14 pm
Forum: Camera board
Topic: Exposure control goes into oscillation during video recordin
Replies: 8
Views: 2116

Re: Exposure control goes into oscillation during video reco

Lots of back lighting is always going to be a pain. And as mentioned above, the tuning hasn't had a huge amount of time spent on it (you can spend man years!). Enough to get a decent image, plus a little bit more, but dealing with this sort of edge case stuff is very time consuming, and there isn't...
by szhorvat
Tue Jun 10, 2014 1:42 pm
Forum: Camera board
Topic: Exposure control goes into oscillation during video recordin
Replies: 8
Views: 2116

Re: Exposure control goes into oscillation during video reco

Has anyone else encountered similar problems, i.e. oscillations in the exposure that do not die off? It looks like the auto-exposure control is not well tuned ...
by szhorvat
Thu Jun 05, 2014 5:36 pm
Forum: Camera board
Topic: Spot metering: how to move the spot?
Replies: 0
Views: 636

Spot metering: how to move the spot?

The Pi camera supports spot metering (raspistill -mm spot). Where is the metering spot and how large is it? How can I move the location of the metering spot? (I'm willing to use any camera API that supports this if not possible with raspistill/raspivid.) Use case: I'm taking a time lapse during vary...
by szhorvat
Thu Jun 05, 2014 3:09 pm
Forum: Wolfram Language
Topic: Any Tutorial for Wolfram?
Replies: 7
Views: 14520

Re: Any Tutorial for Wolfram?

Take a look here. There's a section with tutorials.
by szhorvat
Thu Jun 05, 2014 2:29 pm
Forum: Camera board
Topic: Exposure control goes into oscillation during video recordin
Replies: 8
Views: 2116

Exposure control goes into oscillation during video recordin

I'm trying to use the Pi camera (NoIR version) to record a video in relatively low light. Under these conditions, sometimes the automatic exposure control goes into oscillations: the video gets overly bright, then very dark, then bright, then dark again, etc. The effect is extreme and makes the vide...
by szhorvat
Wed Jun 04, 2014 2:37 am
Forum: Mathematica
Topic: Parallelization
Replies: 4
Views: 4795

Re: Parallelization

From the link you gave it says: "To add kernels through Lightweight Grid, first install gridMathematica with Lightweight Grid on the computers you want to use." It seems ot me that the Mathematica on the RPi is stripped down (no offline manual - no parallel processing) and I get the feeling that Wo...
by szhorvat
Wed Jun 04, 2014 2:29 am
Forum: Mathematica
Topic: Parallelization
Replies: 4
Views: 4795

Re: Parallelization

I do not have multiple Raspberry Pis to test, but based on my experience with the desktop version of Mathematica I am fairly confident that this is possible. I typed up half an answer here, but after a browser crash and a malfunction of this forum's save draft feature I lost it. So here's a shortene...

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