Re: Berlin D Meetup Feb 2015
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 02/27/2015 03:04 PM, Ben Palmer wrote: Wrapping the RNGs can cause problems as structs are passed by value. This means that if the same RNG is used in subsequent calls to say randomCover then the same sequence of random numbers will be produced by each range. A simple solution to this would be make random ranges classes. This can also cause problems but with memory management (we want to avoid lots of small alloc and free events). It also does not address problems with functions that make bad assumptions about their arguments. If we can solve these problems then there are several different avenues to push forward with new RNG wrapper functionality. There are also other opportunities for looking at random number generation. I actually had an idea how to solve this. https://issues.dlang.org/show_bug.cgi?id=7067#c19 -BEGIN PGP SIGNATURE- Version: GnuPG v1 iQIcBAEBAgAGBQJU8i+vAAoJELJzgRYSuxk5u/8P/3znsvHfZ3+hiG4MfLUakBfA PASqYeesud4EBOYf7ztgYqCNziSZ5Zd4/fe9PyzgC1TMRzVfseckhpU9WNaVvtMd Ej5SnY6ylGma3lr9Bfl2EZWU6NgLvwgB/ZIYlJb6WjLyGaQy03niIcOlqEg4rHo/ vLr7qcCqBGGgUB3K+riQRP9ZDrub2JF5F2yad+fZB+bAObgqujENqLd+YiVNvW8p VeuDOacnb7S+tAakIUXOLJ8+peMEgtkhIKiRUjsXR7Q/QjwNLNMwBdTnrPKlyCNH Vt5f8vtzHRadFypHWvYvinNW4d2Eg62IZjYutzLia1AsHfrnCpt5l476gwaQnUa9 Zti22d0m8usKFR/MqUbhZ3c7xqBVcS9ib9JpnGVxnzWmI4zp7/PP8363IEZb84Yg U15vynIpIxMXsL2c8/qTGhL6wYSRX6+7sP+a+ZoBughAGAqSVmfbLhrAzJYg5SMq jEvB49jaWVS8VH/KS/OBHLedUoTad7BpFeMJk+GiGcd3vdhQJPsIv1ji7fCBQtBU 8hFjJsb/GYmihrfa8ds018DhmvV4OgOW1+a8xzYs3oKOQ5cq251U1oq+oh4lKoWO DMjUiPoa0zAMvrFRBirGs3tBO0361/et/hCwxLrKhhoR1mVTdm5kHEIv16SIjQiF W1meFORZw8QGBkvwz5Lm =OjGb -END PGP SIGNATURE-
Re: Berlin D Meetup Feb 2015
I thought I would give a brief summary of the last meetup. Joseph Wakeling gave a presentation entitled “Random number generation in Phobos and beyond”. It was a great talk and we had some interesting discussions afterwards. The talk began by mentioning some naive ways of generating random numbers and some of the negative consequences this can cause. Joseph then mentioned other methods of generating random numbers including big tables of random numbers, physical randomness, and deterministic methods (pseudo-random). Pseudo-random number generators (RNGs) use a state variable and a transition function that maps from the current state to the next state and this sounds like a good match for a forward range. Currently in Phobos all RNGs are implemented as ForwardRange structs. Other ranges such as randomCover and randomSample wrap the Phobos RNGs. Wrapping the RNGs can cause problems as structs are passed by value. This means that if the same RNG is used in subsequent calls to say randomCover then the same sequence of random numbers will be produced by each range. A simple solution to this would be make random ranges classes. This can also cause problems but with memory management (we want to avoid lots of small alloc and free events). It also does not address problems with functions that make bad assumptions about their arguments. If we can solve these problems then there are several different avenues to push forward with new RNG wrapper functionality. There are also other opportunities for looking at random number generation. After the talk there was some discussion on a number of points including: Testing RNGs. The unittests in std.random don't (and can't) provide tests of randomness. There are existing RNG tests in linux. It would be good to get a good randomness test suite in D. Does the c++ standard library have the same problems? Possibly, there was some certainty that the boost documentation has some reference to the same problems. Is this a general problem with forward ranges? Could there be something missing from the range interface or perhaps it would be better to have a distinct range type for random numbers. There was then a discussion of the various types of hardware RNGs. Martin Novak mentioned “haveged” a C program that can generate large numbers of random numbers. It generates randomness based on variations in code execution time on a processor. Thanks, Ben.
Re: Berlin D Meetup Feb 2015
On Thursday, 12 February 2015 at 01:58:04 UTC, Walter Bright wrote: I see you're doing the presentation! I note that you haven't submitted a presentation proposal for Dconf 2015 yet. Please submit this one! Why not get the most mileage out of it? Submitted :-)
Re: Berlin D Meetup Feb 2015
Just a reminder that this is happening tonight at 19:30. For those coming from further away the closest U-Bahn is Kottbusser Tor on the U1 and U8. The directions for getting to the room (from the http://co-up.de/ website) are: Go through the big metal gate to the left of Adalbertstr. 7, straight to the far end of the courtyard, and in the first tunnel to your right. Ring the bell marked co.up 3.OG and come up to the 3rd floor. If you are attending an evening/weekend meetup, you may find the big gate closed. In that case, go back in the direction of Kottbusser Tor to the small gate at Adalbertstr. 5-6. Reach through the bars to turn the handle and make your way straight through the tunnel, left through a second tunnel and then straight past the bike rack until you see the door of our building, across from the mailboxes. Looking forward to seeing everyone and to Joseph's talk.
Re: Berlin D Meetup Feb 2015
On 2/7/2015 1:45 PM, Joseph Rushton Wakeling wrote: On Thursday, 5 February 2015 at 11:14:28 UTC, Ben wrote: The next Berlin D Meetup will be happening on Friday the 20th of February at 19:30. The venue will be Berlin Co-Op (http://co-up.de/) on the 3rd floor who have the equipment for us to do presentations. Speaking of presentations, big thanks to Joseph Wakeling who will be doing a presentation on Random number generation in Phobos and beyond. After the presentation we will have time for questions/discussions/drinks. Oh boy, what have I let myself in for :-) I see you're doing the presentation! I note that you haven't submitted a presentation proposal for Dconf 2015 yet. Please submit this one! Why not get the most mileage out of it?
Re: Berlin D Meetup Feb 2015
On Thursday, 5 February 2015 at 11:14:28 UTC, Ben wrote: The next Berlin D Meetup will be happening on Friday the 20th of February at 19:30. The venue will be Berlin Co-Op (http://co-up.de/) on the 3rd floor who have the equipment for us to do presentations. Speaking of presentations, big thanks to Joseph Wakeling who will be doing a presentation on Random number generation in Phobos and beyond. After the presentation we will have time for questions/discussions/drinks. Oh boy, what have I let myself in for :-)
Berlin D Meetup Feb 2015
Hi All, The next Berlin D Meetup will be happening on Friday the 20th of February at 19:30. The venue will be Berlin Co-Op (http://co-up.de/) on the 3rd floor who have the equipment for us to do presentations. Speaking of presentations, big thanks to Joseph Wakeling who will be doing a presentation on Random number generation in Phobos and beyond. After the presentation we will have time for questions/discussions/drinks. We also have a meetup page here: http://www.meetup.com/Berlin-D-Programmers/ Thanks, Ben.
