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Cuchulainn
Posts: 20255
Joined: July 16th, 2004, 7:38 am
Location: 20, 000

Cool algorithms

January 20th, 2014, 5:42 am

Very good initiative!Here's a list of algorithms
 
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ExSan
Posts: 493
Joined: April 12th, 2003, 10:40 am

Cool algorithms

January 20th, 2014, 10:41 am

QuoteOriginally posted by: outrunXOR linked list, a double linked list using just 1 pointer instead of twoI liked this one, I will figure out how to implement it using C++. does it save some memory ???, it does not speed up anything but it slows down some basic operations like search. am I wrong ?Probably neither it saves some memory, maybe 3 bytes per link at most, because you still need a memory location for the bit wise what about cool parallel algos ? -nice thread, if I find something I will post-
Last edited by ExSan on January 19th, 2014, 11:00 pm, edited 1 time in total.
°°° About ExSan bit.ly/3U5bIdq °°°
 
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farmer
Posts: 61
Joined: December 16th, 2002, 7:09 am

Cool algorithms

January 20th, 2014, 1:00 pm

QuoteOriginally posted by: outrun"A fountain code is a way to take some data - a file, for example - and transform it into an effectively unlimited number of encoded chunks, such that you can reassemble the original file given any subset of those chunks, as long as you have a little more than the size of the original file. In other words, it lets you create a 'fountain' of encoded data; a receiver can reassemble the file by catching enough 'droplets', regardless of which ones they get and which ones they miss.Back when cell phones first became popular, I made a video codec something like this. It would kind of jump around and update the most changed or most interesting parts of the picture. It was sort of like non-linear interleaving. This was before h264 nal units. I wanted a way to overcome the total destruction of video signals from small losses, for transmission of video in a lossy way between two cellphones.I was sort of proud of myself, it did produce informative video. It wasn't something anybody would want to watch. But it did communicate actual events in a way that could conceivably be better than very slow frames from a security camera, for example. There were tracers, and areas of the image that lagged behind or got stuck in one place over an extended period of loss.The idea has some good points, such as that things which move are made of pixels which are closer to each other than any orderly way of proceeding through rows and columns. If a person is walking across an alley, there is no reason to even think about redrawing the corners of the image. h264 does this much better than I can ever dream of, but there may be room for an even greater efficiency in this sort of informational video, if designed by a person with the skills to do so.
 
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dd3
Posts: 4
Joined: June 8th, 2010, 9:02 am

Cool algorithms

January 21st, 2014, 1:24 pm

QuoteOriginally posted by: farmerQuoteOriginally posted by: outrun"A fountain code is a way to take some data - a file, for example - and transform it into an effectively unlimited number of encoded chunks, such that you can reassemble the original file given any subset of those chunks, as long as you have a little more than the size of the original file. In other words, it lets you create a 'fountain' of encoded data; a receiver can reassemble the file by catching enough 'droplets', regardless of which ones they get and which ones they miss.Back when cell phones first became popular, I made a video codec something like this. It would kind of jump around and update the most changed or most interesting parts of the picture. It was sort of like non-linear interleaving. This was before h264 nal units. I wanted a way to overcome the total destruction of video signals from small losses, for transmission of video in a lossy way between two cellphones.I was sort of proud of myself, it did produce informative video. It wasn't something anybody would want to watch. But it did communicate actual events in a way that could conceivably be better than very slow frames from a security camera, for example. There were tracers, and areas of the image that lagged behind or got stuck in one place over an extended period of loss.The idea has some good points, such as that things which move are made of pixels which are closer to each other than any orderly way of proceeding through rows and columns. If a person is walking across an alley, there is no reason to even think about redrawing the corners of the image. h264 does this much better than I can ever dream of, but there may be room for an even greater efficiency in this sort of informational video, if designed by a person with the skills to do so.h264 wasn't the first video codec to do this sort of compression, it's been around for at least a decade.