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• (How) Can I approximate a "dynamic" index (key extractor) for Boost MultiIndex?

  - by Sarah

  I have a MultiIndex container of boost::shared_ptrs to members of class Host. These members contain private arrays bool infections[NUM_SEROTYPES] revealing Hosts' infection statuses with respect to each of 1,...,NUM_SEROTYPES serotypes. I want to be able to determine at any time in the simulation the number of people infected with a given serotype, but I'm not sure how: Ideally, Boost MultiIndex would allow me to sort, for example, by Host::isInfected( int s ), where s is the serotype of interest. From what I understand, MultiIndex key extractors aren't allowed to take arguments. An alternative would be to define an index for each serotype, but I don't see how to write the MultiIndex container typedef ... in such an extensible way. I will be changing the number of serotypes between simulations. (Do experienced programmers think this should be possible? I'll attempt it if so.) There are 2^(NUM_SEROTYPES) possible infection statuses. For small numbers of serotypes, I could use a single index based on this number (or a binary string) and come up with some mapping from this key to actual infection status. Counting is still darn slow. I could maintain a separate structure counting the total numbers of infecteds with each serotype. The synchrony is a bit of a pain, but the memory is fine. I would prefer a slicker option, since I would like to do further sorts on other host attributes (e.g., after counting the number infected with serotype s, count the number of those infected who are also in a particular household and have a particular age). Thanks in advance.

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• Storing multiple discarded datas in a single variable using a string accumulator

  - by dan

  For an assignment for my intro to python course, we are to write a program that generates 100 sets of x,y coordinates. X must be a float between -100.0 and 100.0 inclusive, but not 0. Y is Y = ((1/x) * 3070) but if the absolute value of Y is greater than 100, both numbers must be discarded (BUT STORED) and another set generated. The results must be displayed in a table, and then after the table, the discarded results must be shown. The teacher said we should use a "string accumulator" to store the discarded data. This is what I have so far, and I'm stuck at storing the discarded data. # import random.py import random # import math.py import math # define main def main(): x = random.uniform(-100.0, 100.0) while x == 0: x = random.uniform(-100.0, 100.0) y = ((1/x) * 3070) while math.fabs(y) > 100: xDiscarded = yDiscarded = y = ((1/x) * 3070) As you can see, I run into the problem of when abs(y) 100, I'm not too sure how to store the discarded data and let it accumulate every time abs(y) 100. I'm cool with the data being stored as "351.2, 231.1, 152.2" I just don't know how to turn the variable into a string and store it. We haven't learned arrays yet so I can't do that. Any help would be much appreciated. Thanks!

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• Difference dynami static 2d array c++

  - by snorlaks

  Hello, Im using opensource library called wxFreeChart to draw some XY charts. In example there is code which uses static array as a serie : double data1[][2] = { { 10, 20, }, { 13, 16, }, { 7, 30, }, { 15, 34, }, { 25, 4, }, }; dataset-AddSerie((double *) data1, WXSIZEOF(dynamicArray)); WXSIZEOF ismacro defined like: sizeof(array)/sizeof(array[0]) In this case everything works great but in my program Im using dynamic arrays (according to users input). I made a test and wrotecode like below: double **dynamicArray = NULL; dynamicArray = new double *[5] ; for( int i = 0 ; i < 5 ; i++ ) dynamicArray[i] = new double[2]; dynamicArray [0][0] = 10; dynamicArray [0][1] = 20; dynamicArray [1][0] = 13; dynamicArray [1][1] = 16; dynamicArray [2][0] = 7; dynamicArray [2][1] = 30; dynamicArray [3][0] = 15; dynamicArray [3][1] = 34; dynamicArray [4][0] = 25; dynamicArray [4][1] = 4; dataset-AddSerie((double *) *dynamicArray, WXSIZEOF(dynamicArray)); But it doesnt work correctly. I mean point arent drawn. I wonder if there is any possibility that I can "cheat" that method and give it dynamic array in way it understands it and will read data from correct place thanks for help

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• Any workarounds for non-static member array initialization?

  - by TomiJ

  In C++, it's not possible to initialize array members in the initialization list, thus member objects should have default constructors and they should be properly initialized in the constructor. Is there any (reasonable) workaround for this apart from not using arrays? [Anything that can be initialized using only the initialization list is in our application far preferable to using the constructor, as that data can be allocated and initialized by the compiler and linker, and every CPU clock cycle counts, even before main. However, it is not always possible to have a default constructor for every class, and besides, reinitializing the data again in the constructor rather defeats the purpose anyway.] E.g. I'd like to have something like this (but this one doesn't work): class OtherClass { private: int data; public: OtherClass(int i) : data(i) {}; // No default constructor! }; class Foo { private: OtherClass inst[3]; // Array size fixed and known ahead of time. public: Foo(...) : inst[0](0), inst[1](1), inst[2](2) {}; }; The only workaround I'm aware of is the non-array one: class Foo { private: OtherClass inst0; OtherClass inst1; OtherClass inst2; OtherClass *inst[3]; public: Foo(...) : inst0(0), inst1(1), inst2(2) { inst[0]=&inst0; inst[1]=&inst1; inst[2]=&inst2; }; }; Edit: It should be stressed that OtherClass has no default constructor, and that it is very desirable to have the linker be able to allocate any memory needed (one or more static instances of Foo will be created), using the heap is essentially verboten. I've updated the examples above to highlight the first point.

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• Problem in homemade function to merge objects

  - by Eric

  I'm trying to make a function that merges arrays. The reason is, I have a function that supposed to get the settings of an entity, and merge them with the global defaults. //So for example, let's say globalOptions is something like this var globalOptions={opt1:'foo',opt2:'something'}; //and this is entityOptions var entityOptions={opt1:'foofoo',opt2:null}; The only difference is it has objects in objects and objects in objects in objects, so what I made was a function that loops through all objects, thinking I would later, easily be able to loop through it all. Please ignore the array thing. That is defected, but unneeded. function loopObj(obj, call, where, objcall, array) { if ($.isArray(obj) || $.isPlainObject(obj)) { for (i in obj) { if ($.isArray(obj)) { if (array) { loopObj(obj[i], call, where[where.length] = i, true); if (objcall) { call(obj[i],where,true); } } else { loopObj(obj[i], call, where+'['+i+']', false); if (objcall) { call(obj[i],where,true); } } } else { if (array) { loopObj(obj[i], call, where[where.length] = parseInt(i), true); if (objcall) { call(obj[i],where,true); } } else { loopObj(obj[i], call, where+'[\''+i+'\']', false); if (objcall) { call(obj[i],where,true); } } } } } else { return call(obj,where); } } Then I made this program to convert it: function mergeObj(a,b) { temp.retd = new Object(); loopObj(a,function (c,d) { if (c) { eval(d.replace('%par%','temp.retd'))=c; } else { eval(d.replace('%par%','temp.retd'))=eval(d.replace('%par%','b')); } },'%par%', true); return temp.retd(); } I get the error: Uncaught ReferenceError: Invalid left-hand side in assignment (anonymous function)base.js:51 loopObjbase.js:40 loopObjbase.js:31 mergeObjbase.js:46 (anonymous function)base.js:72 I know what it means, the eval returns an anonomys variable (copy of the variable), so I can't set it, only get it.

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• PHP: parse $_FILES[] data in multidimesional array

  - by superUntitled

  I having been looking around for an answer to this and have not found an answer anywhere, I am hoping someone has done this before! I have a form that allows for dynamic duplication of the form fields. The form allows for file uploads and text input, so the data is sent in both $_POST and $_FILES arrays. The the initial set of inputs look like this: <input type="text" name="primary[1][text]" /> <input type="file" name="primary[1][file]" /> <input type="text" class="a" name="secondary[1][text][]" /> <input type="file" name="secondary[1][file][]" /> When duplicated the fields are incremented, they look like this: <input type="text" name="primary[2][text]" /> <input type="file" name="primary[2][file]" /> <input type="text" class="a" name="secondary[2][text][]" /> <input type="file" name="secondary[2][file][]" /> To complicate matters, the "secondary" form fields can also be duplicated (thus the [] at the end of the secondary name array. How can I parse the posted $_FILES array? I have tried something like this: foreach ($_FILES['question'] as $f_num) { echo $f['file']['name']; } but I get an "Undefined index: file... " error.

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• PHP: parse $_FILES[] data in multidimesional array

  - by superUntitled

  Example form here: http://jsfiddle.net/superuntitled/uaTtx/1/ I have a form that allows for dynamic duplication of the form fields. The form allows for file uploads and text input, so the data is sent in both $_POST and $_FILES arrays. The the initial set of inputs look like this: <input type="text" name="question[1][text]" /> <input type="file" name="question[1][file]" /> <input type="text" class="a" name="answer[1][text][]" /> <input type="file" name="answer[1][file][]" /> When duplicated the fields are incremented, they look like this: <input type="text" name="question[2][text]" /> <input type="file" name="question[2][file]" /> <input type="text" class="a" name="answer[2][text][]" /> <input type="file" name="answer[2][file][]" /> To complicate matters, the "answer" form fields can also be duplicated (thus the [] at the end of the 'answer' name array. How can I parse the posted $_FILES array? I have tried something like this: foreach ($_FILES['question'] as $p_num) { echo $p_num['file']['name']; foreach ($_FILES['answer'] as $a_num) { echo $a_num['file']['name']; } } but I get an "Undefined index: file... " error. How can I parse out the posted values.

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• CakePHP - recursive on specific fields in model?

  - by Paul

  Hi, I'm pretty new to CakePHP but I think I'm starting to get the hang of it. I'm trying to pull related table information recursively, but I want to specify which related models to recurse on. Let me give you an example to demonstrate my goal: I have a model "Customer", which has info like Company name, website, etc. "Customer" hasMany "Addresses", which contain info for individual contacts like Contact Name, Street, City, State, Country, etc. "Customer" also belongsTo "CustomerType", which is just has descriptive category info - a name and description, like "Distributor" or "Manufacturer". When I do a find on "Customer" I want to get associated "CustomerType" and "Address" info as sub-arrays, and this works fine just by setting up the hasMany and belongsTo associations properly. But now, here's my issue: I want to get associated State/Country info. So, instead of each "Address" array row just having "state_id", I want it to have "state" = array("id" = 20, "name" = "New York",...) etc. If I set $recursive to a higher value (e.g., 2) in the Partner model, I get what I want for the State/Country info in each "Address". BUT it also recurses on "CustomerType", and that results in the "CustomerType" field of my "Partner" object having a huge array of all Customer objects that match that type, which could be thousands long. So the point is, I DON'T want to recurse on "CustomerType", only on "Address". Is there a way I can set this up? Sorry for the long-winded question, and thanks in advance!

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• Error logging/handling on application basis?

  - by Industrial

  Hi everybody, We have a web server that we're about to launch a number of applications on. On the server-level we have managed to work out the error handling with the help of Hyperic to notify the person who is in charge in the event of a database/memcached server is going down. However, we are still in the need of handling those eventual error and log events that happen on application level to improve the applications for our customers, before the customers notices. So, what's then a good solution to do this? Utilizing PHP:s own error log would quickly become cloggered if we would run a big number of applications at the same time. It's probably isn't the best option if you like structure. One idea is to build a off-site lightweight error-handling application that has a REST/JSON API that receives encrypted and serialized arrays of error messages and stores them into a database. Maybe it could, depending on the severity of the error also be directly inputted into our bug tracker. Could be a few well spent hours, but it seems like a quite fragile solution and I am sure that there's better more-reliable alternatives out there already. Thanks,

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• How to easily apply a function to a collection in C++

  - by Jesse Beder

  I'm storing images as arrays, templated based on the type of their elements, like Image<unsigned> or Image<float>, etc. Frequently, I need to perform operations on these images; for example, I might need to add two images, or square an image (elementwise), and so on. All of the operations are elementwise. I'd like get as close as possible to writing things like: float Add(float a, float b) { return a+b; } Image<float> result = Add(img1, img2); and even better, things like complex ComplexCombine(float a, float b) { return complex(a, b); } Image<complex> result = ComplexCombine(img1, img2); or struct FindMax { unsigned currentMax; FindMax(): currentMax(0) {} void operator(unsigned a) { if(a > currentMax) currentMax = a; } }; FindMax findMax; findMax(img); findMax.currentMax; // now contains the maximum value of 'img' Now, I obviously can't exactly do that; I've written something so that I can call: Image<float> result = Apply(img1, img2, Add); but I can't seem to figure out a generic way for it to detect the return type of the function/function object passed, so my ComplexCombine example above is out; also, I have to write a new one for each number of arguments I'd like to pass (which seems inevitable). Any thoughts on how to achieve this (with as little boilerplate code as possible)?

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• How to optimize this simple function which translates input bits into words?

  - by psihodelia

  I have written a function which reads an input buffer of bytes and produces an output buffer of words where every word can be either 0x0081 for each ON bit of the input buffer or 0x007F for each OFF bit. The length of the input buffer is given. Both arrays have enough physical place. I also have about 2Kbyte free RAM which I can use for lookup tables or so. Now, I found that this function is my bottleneck in a real time application. It will be called very frequently. Can you please suggest a way how to optimize this function? I see one possibility could be to use only one buffer and do in-place substitution. void inline BitsToWords(int8 *pc_BufIn, int16 *pw_BufOut, int32 BufInLen) { int32 i,j,z=0; for(i=0; i<BufInLen; i++) { for(j=0; j<8; j++, z++) { pw_BufOut[z] = ( ((pc_BufIn[i] >> (7-j))&0x01) == 1? 0x0081: 0x007f ); } } } Please do not offer any compiler specific or CPU/Hardware specific optimization, because it is a multi-platform project.

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• looping array inside list in c#

  - by 3yoon af

  I have a list of array that contains multiple arrays. each array has 2 index .. First, I want to loop the list. Then i want to loop the array inside the list .. How can i do that ? I try to use this way, but it doesn't work ! foreach (string[] s in ArrangList1) { int freq1 = int.Parse(s[1]); foreach (string[] s1 in ArrangList) { int freq2 = int.Parse(s1[1]); if (freq1 < freq2) { backup = s; index1 = ArrangList1.IndexOf(s); index2 = ArrangList.IndexOf(s1); ArrangList[index1] = s1; ArrangList[index2] = s; } backup = null; } } it give me error in line 4.. I try to do the loop using other way .. but i don't know how to continue ! for (int i = 0; i < ArrangList1.Count; i++) { for (int j = 0; j < ArrangList1[i].Length; j++) { ArrangList1[i][1]; } } I use C# language .. Can someone help me, please?

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• Optimizing near-duplicate value search

  - by GApple

  I'm trying to find near duplicate values in a set of fields in order to allow an administrator to clean them up. There are two criteria that I am matching on One string is wholly contained within the other, and is at least 1/4 of its length The strings have an edit distance less than 5% of the total length of the two strings The Pseudo-PHP code: foreach($values as $value){ foreach($values as $match){ if( ( $value['length'] < $match['length'] && $value['length'] * 4 > $match['length'] && stripos($match['value'], $value['value']) !== false ) || ( $match['length'] < $value['length'] && $match['length'] * 4 > $value['length'] && stripos($value['value'], $match['value']) !== false ) || ( abs($value['length'] - $match['length']) * 20 < ($value['length'] + $match['length']) && 0 < ($match['changes'] = levenshtein($value['value'], $match['value'])) && $match['changes'] * 20 <= ($value['length'] + $match['length']) ) ){ $matches[] = &$match; } } } I've tried to reduce calls to the comparatively expensive stripos and levenshtein functions where possible, which has reduced the execution time quite a bit. However, as an O(n^2) operation this just doesn't scale to the larger sets of values and it seems that a significant amount of the processing time is spent simply iterating through the arrays. Some properties of a few sets of values being operated on Total | Strings | # of matches per string | | Strings | With Matches | Average | Median | Max | Time (s) | --------+--------------+---------+--------+------+----------+ 844 | 413 | 1.8 | 1 | 58 | 140 | 593 | 156 | 1.2 | 1 | 5 | 62 | 272 | 168 | 3.2 | 2 | 26 | 10 | 157 | 47 | 1.5 | 1 | 4 | 3.2 | 106 | 48 | 1.8 | 1 | 8 | 1.3 | 62 | 47 | 2.9 | 2 | 16 | 0.4 | Are there any other things I can do to reduce the time to check criteria, and more importantly are there any ways for me to reduce the number of criteria checks required (for example, by pre-processing the input values), since there is such low selectivity?

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• Problem using find function in Matlab

  - by Peter Etchells

  Hi all, I have two arrays of data that I'm trying to amalgamate. One contains actual latencies from an experiment in the first column (e.g. 0.345, 0.455... never more than 3 decimal places), along with other data from that experiment. The other contains what is effectively a 'look up' list of latencies ranging from 0.001 to 0.500 in 0.001 increments, along with other pieces of data. Both data sets are X-by-Y doubles. What I'm trying to do is something like... for i = 1:length(actual_latency) row = find(predicted_data(:,1) == actual_latency(i) full_set(i,1:4) = [actual_latency(i) other_info(i) predicted_info(row,2)... predicted_info(row,3)]; end ...in order to find the relevant row in predicted_data where the look up latency corresponds to the actual latency. I then use this to created an amalgamated data set, full_set. I figured this would be really simple, but the find function keeps failing by throwing up an empty matrix when looking for an actual latency that I know is in predicted_data(:,1) (as I've double-checked during debugging). Moreover, if I replace find with a for loop to do the same job, I get a similar error. It doesn't appear to be systematic - using different participant data sets throws it up in different places. Furthermore, during debugging mode, if I use find to try and find a hard-coded value of actual_latency, it doesn't always work. Sometimes yes, sometimes no. I'm really scratching my head over this, so if anyone has any ideas about what might be going on, I'd be really grateful.

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• Applying a function that may fail to all values in a list

  - by Egwor

  I want to apply a function f to a list of values, however function f might randomly fail (it is in effect making a call out to a service in the cloud). I thought I'd want to use something like map, but I want to apply the function to all elements in the list and afterwards, I want to know which ones failed and which were successful. Currently I am wrapping the response objects of the function f with an error pair which I could then effectively unzip afterwards i.e. something like g : (a->b) -> a -> [ b, errorBoolean] f : a-> b and then to run the code ... map g (xs) Is there a better way to do this? The other alternative approach was to iterate over the values in the array and then return a pair of arrays, one which listed the successful values and one which listed the failures. To me, this seems to be something that ought to be fairly common. Alternatively I could return some special value. What's the best practice in dealing with this??

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• OpenType Font Parsing for Pleasure and Profit (anyone understand these damn tables?)

  - by mustISignUp

  So, this is mainly for fun, I'm poking around and trying to find my way inside a few fonts and i have a few questions i'd reeally appreciate some help on if anyone has done this kind of stuff. cmap table The fonts i am testing with contain several cmap subtables of different formats. I can read them, but i don't understand which i should be using. ie. what is the strategy for choosing the most appropriate subtable? Does this even make sense? glyf table This is really making my head hurt. I'm going by what is on here. Looking at the second table on that page.. I've got 'n' endPtsOfContours, 'n' instructions and 'n' flags but it is not clear to me if i have the same number of flags as contours (i know how many contours i have). Then, to make matters worse..(fun!) i have an array of xCoords and an array of yCoords. These arrays seem to be of indeterminate length and may contain data of either BYTE or SHORT but we are not going to tell you which.. Thanks to anyone willing to shed some light.

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• Beginnerquestion: How to count amount of each number drawn in a Lottery and output it in a list?

  - by elementz

  I am writing this little Lottery application. Now the plan is, to count how often each number has been drawn during each iteration of the Lottery, and store this somewhere. My guess is that I would need to use a HashMap, that has 6 keys and increments the value by one everytime the respective keys number is drawn. But how would I accomplish this? My code so far: public void numberCreator() { // creating and initializing a Random generator Random rand = new Random(); // A HashMap to store the numbers picked. HashMap hashMap = new HashMap(); // A TreeMap to sort the numbers picked. TreeMap treeMap = new TreeMap(); // creating an ArrayList which will store the pool of availbale Numbers List<Integer>numPool = new ArrayList<Integer>(); for (int i=1; i<50; i++){ // add the available Numbers to the pool numPool.add(i); hashMap.put(nums[i], 0); } // array to store the lotto numbers int [] nums = new int [6]; for (int i =0; i < nums.length; i++){ int numPoolIndex = rand.nextInt(numPool.size()); nums[i] = numPool.get(numPoolIndex); // check how often a number has been called and store the new amount in the Map int counter = hashMap.get numPool.remove(numPoolIndex); } System.out.println(Arrays.toString(nums)); } Maybe someone can tell me if I have the right idea, or even how I would implement the map properly?

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• [Rails3] How to do multiple many to many relationships between the same two tables.

  - by Kurt

  Hi. I have a model of a club where I want to model the two entities Meeting and Member. There are actually two many-to-many relationships between these entities though, as for any meeting a Member can either be a Speaker or a Guest. Now I am an OO thinker, so would normally just create the two classes and each one would just have two arrays of the other inside, but rails is making me think a bit more data centric here, so I realise I need to break these M2M relationships up with join tables Speakers and Guests which I have done, but now I am having trouble describing the relationships in the models. The two join table models both have "belongs_to :meeting" and "belongs_to :member" and I think that should be sufficient. I am not however sure about the Meeting and Member models though. Each one has "has_many :guests" and "has_many: speakers" but I am not sure if I also want to go: has_many :members, :through = :guests has_many :members, :through = :speakers But I suspect that this is like declaring two "members" that will clash. I also thought about: has_many :guests, :through = :guests has_many :speakers, :through = :speakers Does that make sense? How would ActiveRecord know that they are in fact Members? I have found heaps of examples of polymorphic m2m relationships and m2m relationships where 1 table references itself, but no good examples to help me mode this situation where two separate tables have two different m2m relationships. Anyone got any tips?

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• C Map String to Function

  - by Scriptonaut

  So, I'm making a Unix minishell, and have come to a roadblock. I need to be able to execute built-in functions, so I made a function: int exec_if_built_in(char **args) It takes an array of strings(the first being the command, and the rest being arguments). For non built-in commands I simply use something like execvp, however I need to find a way to map the first string to a function. I was thinking of making two arrays, one of strings, and another with their corresponding function pointers. However, since many of these functions will be different(return and accept different things), this approach won't work. I also thought of making an array of structs with a name property and a function pointer property, however once again due to the varied nature of the functions I'll be using, this won't work. So, what's the best way to execute a function based on the input of a string? How do I map a string to a certain function? I'm not very familiar with function pointers so I may be missing something. Thank you guys for the help :)

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• Java servlet's request parameter's name set to entire json object

  - by Geren White

  I'm sending a json object through ajax to a java servlet. The json object is key-value type with three keys that point to arrays and a key that points to a single string. I build it in javascript like this: var jsonObject = {"arrayOne": arrayOne, "arrayTwo": arrayTwo, "arrayThree": arrThree, "string": stringVar}; I then send it to a java servlet using ajax as follows: httpRequest.open('POST', url, true); httpRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); httpRequest.setRequestHeader("Connection", "close"); var jsonString = jsonObject.toJSONString(); httpRequest.send(jsonString); This will send the string to my servlet, but It isn't showing as I expect it to. The whole json string gets set to the name of one of my request's parameters. So in my servlet if I do request.getParameterNames(); It will return an enumeration with one of the table entries' key's to be the entire object contents. I may be mistaken, but my thought was that it should set each key to a different parameter name. So I should have 4 parameters, arrayOne, arrayTwo, arrayThree, and string. Am I doing something wrong or is my thinking off here? Any help is appreciated. Thanks

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• Using MPI_Type_Vector and MPI_Gather, in C.

  - by Goloneg

  Hi, I am trying to multiply square matrices in parallele with MPI. I use a MPI_Type_vector to send square submatrixes (arrays of float) to the processes, so they can calculate subproducts. Then, for the next iterations, these submatrices are send to neighbours processes as MPI_Type_contiguous (the whole submatrix is sent). This part is working as expected, and local results are corrects. Then, I use MPI_Gather with the contiguous types to send all local results back to the root process. The problem is, the final matrix is build (obviously, by this method) line by line instead of submatrix by submatrix. I wrote an ugly procedure rearranging the final matrix, but I would like to know if there is a direct way of performing the "inverse" operation of sending MPI_Type_vectors (i.e., sending an array of values and directly arranging it in a subarray form in the receiving array). An example, to try and clarify my long text : A[16] and B[16] are 4x4 matrices to be multiplied ; C[16] will contain the result ; 4 processes are used (Pi with i from 0 to 3) : Pi gets two 2x2 submatrices : subAi[4] and subBi[4] ; their product is stored locally in subCi[4]. For instance, P0 gets : subA0[4] containing A[0], A[1], A[4] and A[5] ; subB0[4] containing B[0], B[1], B[4] and B[5]. After everything is calculed, root process gathers all subCi[4]. Then C[16] contains : [ subC0[0], subC0[1], subC0[2], subC0[3], subC1[0], subC1[1], subC1[2], subC1[3], subC2[0], subC2[1], subC2[2], subC2[3], subC3[0], subC3[1], subC3[2], subC3[3]] and I would like it to be : [ subC0[0], subC0[1], subC1[0], subC1[1], subC0[2], subC0[3], subC1[2], subC1[3], subC2[0], subC2[1], subC3[0], subC3[1], subC2[2], subC2[3], subC3[2], subC3[3]] without further operation. Does someone know a way ? Thanks for your advices.

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• Scan file contents into an array of a structure.

  - by ZaZu

  Hello, I have a structure in my program that contains a particular array. I want to scan a random file with numbers and put the contents into that array. This is my code : ( NOTE : This is a sample from a bigger program, so I need the structure and arrays as declared ) The contents of the file are basically : 5 4 3 2 5 3 4 2 #include<stdio.h> #define first 500 #define sec 500 struct trial{ int f; int r; float what[first][sec]; }; int trialtest(trial *test); main(){ trial test; trialtest(&test); } int trialtest(trial *test){ int z,x,i; FILE *fin; fin=fopen("randomfile.txt","r"); for(i=0;i<5;i++){ fscanf(fin,"%5.2f\t",(*test).what[z][x]); } fclose(fin); return 0; } But the problem is, whenever this I run this code, I get this error : (25) : warning 508 - Data of type 'double' supplied where a pointer is required I tried adding do{ for(i=0;i<5;i++){ q=fscanf(fin,"%5.2f\t",(*test).what[z][x]); } }while(q!=EOF); But that didnt work either, it gives the same error. Does anyone have a solution to this problem ?

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• STLifying C++ classes

  - by shambulator

  I'm trying to write a class which contains several std::vectors as data members, and provides a subset of vector's interface to access them: class Mesh { public: private: std::vector<Vector3> positions; std::vector<Vector3> normals; // Several other members along the same lines }; The main thing you can do with a mesh is add positions, normals and other stuff to it. In order to allow an STL-like way of accessing a Mesh (add from arrays, other containers, etc.), I'm toying with the idea of adding methods like this: public: template<class InIter> void AddNormals(InIter first, InIter last); Problem is, from what I understand of templates, these methods will have to be defined in the header file (seems to make sense; without a concrete iterator type, the compiler doesn't know how to generate object code for the obvious implementation of this method). Is this actually a problem? My gut reaction is not to go around sticking huge chunks of code in header files, but my C++ is a little rusty with not much STL experience outside toy examples, and I'm not sure what "acceptable" C++ coding practice is on this. Is there a better way to expose this functionality while retaining an STL-like generic programming flavour? One way would be something like this: (end list) class RestrictedVector<T> { public: RestrictedVector(std::vector<T> wrapped) : wrapped(wrapped) {} template <class InIter> void Add(InIter first, InIter last) { std::copy(first, last, std::back_insert_iterator(wrapped)); } private: std::vector<T> wrapped; }; and then expose instances of these on Mesh instead, but that's starting to reek a little of overengineering :P Any advice is greatly appreciated!

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• Array Intersect giving wrong output

  - by Pankaj Khurana

  Hi, I need to find common elements between two arrays. My code is: $sql="SELECT DISTINCT fk_paytbl_discounts_discountid as discountid from paytbl_discounts_students WHERE fk_vtiger_cf_601='".$categoryid."'"; $discountstudentinfo=$objdb->customQuery($sql,false); $sql1="SELECT DISTINCT fk_paytbl_discounts_discountid as discountid from paytbl_discounts_variants WHERE fk_vtiger_products_productid='".$variantid."'"; $discountvariantinfo=$objdb->customQuery($sql1,false); $commondiscount=array_intersect($discountvariantinfo,$discountstudentinfo); First array Array ( [0] => Array ( [discountid] => 2 ) [1] => Array ( [discountid] => 8 ) [2] => Array ( [discountid] => 5 ) [3] => Array ( [discountid] => 4 ) ) Second array Array ( [0] => Array ( [discountid] => 1 ) [1] => Array ( [discountid] => 5 ) ) Common array Array ( [0] => Array ( [discountid] => 1 ) [1] => Array ( [discountid] => 5 ) ) Common array should have only discountid 5 but its showing 1 also. Please help me on this Thanks

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• Value types of variable size

  - by YellPika

  I'm trying to code a small math library in C#. I wanted to create a generic vector structure where the user could define the element type (int, long, float, double, etc.) and dimensions. My first attempt was something like this... public struct Vector<T> { public readonly int Dimensions; public readonly T[] Elements; // etc... } Unfortunately, Elements, being an array, is also a reference type. Thus, doing this, Vector<int> a = ...; Vector<int> b = a; a[0] = 1; b[0] = 2; would result in both a[0] and b[0] equaling 2. My second attempt was to define an interface IVector<T>, and then use Reflection.Emit to automatically generate the appropriate type at runtime. The resulting classes would look roughly like this: public struct Int32Vector3 : IVector<T> { public int Element0; public int Element1; public int Element2; public int Dimensions { get { return 3; } } // etc... } This seemed fine until I found out that interfaces seem to act like references to the underlying object. If I passed an IVector to a function, and changes to the elements in the function would be reflected in the original vector. What I think is my problem here is that I need to be able to create classes that have a user specified number of fields. I can't use arrays, and I can't use inheritance. Does anyone have a solution? EDIT: This library is going to be used in performance critical situations, so reference types are not an option.

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