madman - Developer IT

passing multiple vectors to function by reference (using structure)

- by madman

Hi StackOverflow, Can someone tell me the correct way of passing multiple vectors to a function that can take only a single argument? (specifically for pthread_create (..) function) I tried the following but it does not seem to work :-( First, I created the following structure struct ip2 { void* obj; int dim; int n_s; vector<vector<vector<double> > > *wlist; vector<int> *nrsv; struct model *pModel; }; The threads that I have created actually needs all these parameters. Since im using pthreads_create I put all this in a structure and then passed the pointer to the structure as an argument to pthread_create (as shown). some_fxn() { //some code struct ip2 ip; ip.obj=(void*) this; ip.n_s=n_s; ip.wlist=&wlist; ip.nrsv=&nrsv; ip.pModel=pModel; ip.dim=dim; pthread_create(&callThd1[lcntr], &attr1, &Cls::Entry, (void*) &ip); } The Entry method looks something like this. void* Cls::Entry(void *ip) { struct ip2 *x; x = (struct ip2 *)ip; (reinterpret_cast<Cls1 *>(x->obj))->Run(x->dim,x->n_s, x->wlist, x->nrsv, x->pModel); } The Run method looks something like this. void Run(int dim, int n_c, vector<vector<vector<double> > > *wlist, vector<int> *nrsv, struct model* pModel ) { //some code for(int k = 0; k < n_c; ++k) { //some code end = index + nrsv[k]; //some code } I get the following error when I try to compile the program. error: no match for ‘operator+’ in ‘index + *(((std::vector<int, std::allocator<int> >*)(((unsigned int)k) * 12u)) + nrsv)’ Can someone tell me how to do it the right way. Madhavan

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Avoding multiple thread spawns in pthreads

- by madman

Hi StackOverflow, I have an application that is parallellized using pthreads. The application has a iterative routine call and a thread spawn within the rountine (pthread_create and pthread_join) to parallelize the computation intensive section in the routine. When I use an instrumenting tool like PIN to collect the statistics the tool reports statistics for several threads(no of threads x no of iterations). I beleive it is because it is spawning new set of threads each time the routine is called. How can I ensure that I create the thread only once and all successive calls use the threads that have been created first. When I do the same with OpenMP and then try to collect the statistics, I see that the threads are created only once. Is it beacause of the OpenMP runtime ? Thanks.

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ColdFusion vs PHP

- by Drek

Can anyone share with me (without fervent evangelism, please) any comparative experiences you might have with regard to ColdFusion and PHP in developing internal enterprise browser-based applications? Specifically (but not limited to): 1: Do the rapid-development characteristics of ColdFusion compensate for any performance issues resulting from the additional overhead? 2: Is either particularly suited to individual or team development? 3: Is rapidly developing an application in ColdFusion and then porting it to PHP to improve performance a proposition that only a madman or venture capitalist would consider?

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Trying to get a PC to boot off a bootable SD card that is inside an USB attached Android device.

- by Cyril

First, I'd like to make myself look less a madman than I may have appeared to be. I wanted to have a bootable USB stick with me at all times, but it's less convenient because it's an extra object and it's easier to lose, forget etc. Then I thought, I have an Android phone, and it has a micro SD in it; perfect. Not all PC's can boot off a card reader, but the phone itself is a card reader when attached as a disk drive. Or at least so I thought. Turns out that my netbook BIOS (tested on Asus eeePC) refuses to see it as an external harddrive; it only recognizes it as a generic USB device and doesn't offer an option to boot from it. The device has a name "Android phone" or smth, so it seems to me that it doesn't work as a "pure" card reader, and instead still manifests itself as a phone. Can it be somehow overridden?

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C#, UTF-8 and encoding characters

- by AspNyc

This is a shot-in-the-dark, and I apologize in advance if this question sounds like the ramblings of a madman. As part of an integration with a third party, I need to UTF8-encode some string info using C# so I can send it to the target server via multipart form. The problem is that they are rejecting some of my submissions, probably because I'm not encoding their contents correctly. Right now, I'm trying to figure out how a dash or hyphen -- I can't tell which it is just by looking at it -- is received or interpreted by the target server as ?~@~S (yes, that's a 5-character string and is not your browser glitching out). And unfortunately I don't have a thorough enough understanding of Encoding.UTF8.GetBytes() to know how to use the byte array to begin identifying where the problem might lie. If anybody can provide any tips or advice, I would greatly appreciate it. So far my only friend has been MSDN, and not much of one at that.

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Social Targeting: This One's Just for You

- by Mike Stiles

Think of social targeting in terms of the archery competition we just saw in the Olympics. If someone loaded up 5 arrows and shot them straight up into the air all at once, hoping some would land near the target, the world would have united in laughter. But sadly for hysterical YouTube video viewing, that’s not what happened. The archers sought to maximize every arrow by zeroing in on the spot that would bring them the most points. Marketers have always sought to do the same. But they can only work with the tools that are available. A firm grasp of the desired target does little good if the ad products aren’t there to deliver that target. On the social side, both Facebook and Twitter have taken steps to enhance targeting for marketers. And why not? As the demand to monetize only goes up, they’re quite motivated to leverage and deliver their incredible user bases in ways that make economic sense for advertisers. You could target keywords on Twitter with promoted accounts, and get promoted tweets into search. They would surface for your followers and some users that Twitter thought were like them. Now you can go beyond keywords and target Twitter users based on 350 interests in 25 categories. How does a user wind up in one of these categories? Twitter looks at that user’s tweets, they look at whom they follow, and they run data through some sort of Twitter secret sauce. The result is, you have a much clearer shot at Twitter users who are most likely to welcome and be responsive to your tweets. And beyond the 350 interests, you can also create custom segments that find users who resemble followers of whatever Twitter handle you give it. That means you can now use boring tweets to sell like a madman, right? Not quite. This ad product is still quality-based, meaning if you’re not putting out tweets that lead to interest and thus, engagement, that tweet will earn a low quality score and wind up costing you more under Twitter’s auction system to maintain. That means, as the old knight in “Indiana Jones and the Last Crusade” cautions, “choose wisely” when targeting based on these interests and categories to make sure your interests truly do line up with theirs. On the Facebook side, they’re rolling out ad targeting that uses email addresses, phone numbers, game and app developers’ user ID’s, and eventually addresses for you bigger brands. Why? Because you marketers asked for it. Here you were with this amazing customer list but no way to reach those same customers should they be on Facebook. Now you can find and communicate with customers you gathered outside of social, and use Facebook to do it. Fair to say such users are a sensible target and will be responsive to your message since they’ve already bought something from you. And no you’re not giving your customer info to Facebook. They’ll use something called “hashing” to make sure you don’t see Facebook user data (beyond email, phone number, address, or user ID), and Facebook can’t see your customer data. The end result, social becomes far more workable and more valuable to marketers when it delivers on the promise that made it so exciting in the first place. That promise is the ability to move past casting wide nets to the masses and toward concentrating marketing dollars efficiently on the targets most likely to yield results.

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Simplifying loop in Objective-C

- by Joe Habadas

I have this enormous loop in my code (not by choice), because I can't seem to make it work any other way. If there's some way make this simple as opposed to me repeating it +20 times that would be great, thanks. for (NSUInteger i = 0; i < 20; i++) { if (a[0] == 0xFF || b[i] == a[0]) { c[0] = b[i]; if (d[0] == 0xFF) { d[0] = c[0]; } ... below repeats +18 more times with [i+2,3,4,etc] ... if (a[1] == 0xFF || b[i + 1] == a[1]) { c[1] = b[i + 1]; if (d[1] == 0xFF) { d[1] = c[1]; } ... when it reaches the last one it calls a method ... [self doSomething]; continue; i += 19; ... then } repeats +19 times (to close things)... } } } I've tried almost every possible combo of things that I know of attempting to make this smaller and efficient. Take a look at my flow chart — pretty huh? i'm not a madman, honest.

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Help:Graph contest problem: maybe a modified Dijkstra or another alternative algorithm

- by newba

Hi you all, I'm trying to do this contest exercise about graphs: XPTO is an intrepid adventurer (a little too temerarious for his own good) who boasts about exploring every corner of the universe, no matter how inhospitable. In fact, he doesn't visit the planets where people can easily live in, he prefers those where only a madman would go with a very good reason (several millions of credits for instance). His latest exploit is trying to survive in Proxima III. The problem is that Proxima III suffers from storms of highly corrosive acids that destroy everything, including spacesuits that were especially designed to withstand corrosion. Our intrepid explorer was caught in a rectangular area in the middle of one of these storms. Fortunately, he has an instrument that is capable of measuring the exact concentration of acid on each sector and how much damage it does to his spacesuit. Now, he only needs to find out if he can escape the storm. Problem The problem consists of finding an escape route that will allow XPTOto escape the noxious storm. You are given the initial energy of the spacesuit, the size of the rectangular area and the damage that the spacesuit will suffer while standing in each sector. Your task is to find the exit sector, the number of steps necessary to reach it and the amount of energy his suit will have when he leaves the rectangular area. The escape route chosen should be the safest one (i.e., the one where his spacesuit will be the least damaged). Notice that Rodericus will perish if the energy of his suit reaches zero. In case there are more than one possible solutions, choose the one that uses the least number of steps. If there are at least two sectors with the same number of steps (X1, Y1) and (X2, Y2) then choose the first if X1 < X2 or if X1 = X2 and Y1 < Y2. Constraints 0 < E = 30000 the suit's starting energy 0 = W = 500 the rectangle's width 0 = H = 500 rectangle's height 0 < X < W the starting X position 0 < Y < H the starting Y position 0 = D = 10000 the damage sustained in each sector Input The first number given is the number of test cases. Each case will consist of a line with the integers E, X and Y. The following line will have the integers W and H. The following lines will hold the matrix containing the damage D the spacesuit will suffer whilst in the corresponding sector. Notice that, as is often the case for computer geeks, (1,1) corresponds to the upper left corner. Output If there is a solution, the output will be the remaining energy, the exit sector's X and Y coordinates and the number of steps of the route that will lead Rodericus to safety. In case there is no solution, the phrase Goodbye cruel world! will be written. Sample Input 3 40 3 3 7 8 12 11 12 11 3 12 12 12 11 11 12 2 1 13 11 11 12 2 13 2 14 10 11 13 3 2 1 12 10 11 13 13 11 12 13 12 12 11 13 11 13 12 13 12 12 11 11 11 11 13 13 10 10 13 11 12 8 3 4 7 6 4 3 3 2 2 3 2 2 5 2 2 2 3 3 2 1 2 2 3 2 2 4 3 3 2 2 4 1 3 1 4 3 2 3 1 2 2 3 3 0 3 4 10 3 4 7 6 3 3 1 2 2 1 0 2 2 2 4 2 2 5 2 2 1 3 0 2 2 2 2 1 3 3 4 2 3 4 4 3 1 1 3 1 2 2 4 2 2 1 Sample Output 12 5 1 8 Goodbye cruel world! 5 1 4 2 Basically, I think we have to do a modified Dijkstra, in which the distance between nodes is the suit's energy (and we have to subtract it instead of suming up like is normal with distances) and the steps are the ....steps made along the path. The pos with the bester binomial (Energy,num_Steps) is our "way out". Important : XPTO obviously can't move in diagonals, so we have to cut out this cases. I have many ideas, but I have such a problem implementing them... Could someone please help me thinking about this with some code or, at least, ideas? Am I totally wrong?

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