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  • Find all A^x in a given range

    - by Austin Henley
    I need to find all monomials in the form AX that when evaluated falls within a range from m to n. It is safe to say that the base A is greater than 1, the power X is greater than 2, and only integers need to be used. For example, in the range 50 to 100, the solutions would be: 2^6 3^4 4^3 My first attempt to solve this was to brute force all combinations of A and X that make "sense." However this becomes too slow when used for very large numbers in a big range since these solutions are used in part of much more intensive processing. Here is the code: def monoSearch(min, max): base = 2 power = 3 while 1: while base**power < max: if base**power > min: print "Found " + repr(base) + "^" + repr(power) + " = " + repr(base**power) power = power + 1 base = base + 1 power = 3 if base**power > max: break I could remove one base**power by saving the value in a temporary variable but I don't think that would make a drastic effect. I also wondered if using logarithms would be better or if there was a closed form expression for this. I am open to any optimizations or alternatives to finding the solutions.

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  • Optimising ruby regexp -- lots of match groups

    - by Farcaller
    I'm working on a ruby baser lexer. To improve performance, I joined up all tokens' regexps into one big regexp with match group names. The resulting regexp looks like: /\A(?<__anonymous_-1038694222803470993>(?-mix:\n+))|\A(?<__anonymous_-1394418499721420065>(?-mix:\/\/[\A\n]*))|\A(?<__anonymous_3077187815313752157>(?-mix:include\s+"[\A"]+"))|\A(?<LET>(?-mix:let\s))|\A(?<IN>(?-mix:in\s))|\A(?<CLASS>(?-mix:class\s))|\A(?<DEF>(?-mix:def\s))|\A(?<DEFM>(?-mix:defm\s))|\A(?<MULTICLASS>(?-mix:multiclass\s))|\A(?<FUNCNAME>(?-mix:![a-zA-Z_][a-zA-Z0-9_]*))|\A(?<ID>(?-mix:[a-zA-Z_][a-zA-Z0-9_]*))|\A(?<STRING>(?-mix:"[\A"]*"))|\A(?<NUMBER>(?-mix:[0-9]+))/ I'm matching it to my string producing a MatchData where exactly one token is parsed: bigregex =~ "\n ... garbage" puts $~.inspect Which outputs #<MatchData "\n" __anonymous_-1038694222803470993:"\n" __anonymous_-1394418499721420065:nil __anonymous_3077187815313752157:nil LET:nil IN:nil CLASS:nil DEF:nil DEFM:nil MULTICLASS:nil FUNCNAME:nil ID:nil STRING:nil NUMBER:nil> So, the regex actually matched the "\n" part. Now, I need to figure the match group where it belongs (it's clearly visible from #inspect output that it's _anonymous-1038694222803470993, but I need to get it programmatically). I could not find any option other than iterating over #names: m.names.each do |n| if m[n] type = n.to_sym resolved_type = (n.start_with?('__anonymous_') ? nil : type) val = m[n] break end end which verifies that the match group did have a match. The problem here is that it's slow (I spend about 10% of time in the loop; also 8% grabbing the @input[@pos..-1] to make sure that \A works as expected to match start of string (I do not discard input, just shift the @pos in it). You can check the full code at GH repo. Any ideas on how to make it at least a bit faster? Is there any option to figure the "successful" match group easier?

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  • How can I speed-up this loop (in C)?

    - by splicer
    Hi! I'm trying to parallelize a convolution function in C. Here's the original function which convolves two arrays of 64-bit floats: void convolve(const Float64 *in1, UInt32 in1Len, const Float64 *in2, UInt32 in2Len, Float64 *results) { UInt32 i, j; for (i = 0; i < in1Len; i++) { for (j = 0; j < in2Len; j++) { results[i+j] += in1[i] * in2[j]; } } } In order to allow for concurrency (without semaphores), I created a function that computes the result for a particular position in the results array: void convolveHelper(const Float64 *in1, UInt32 in1Len, const Float64 *in2, UInt32 in2Len, Float64 *result, UInt32 outPosition) { UInt32 i, j; for (i = 0; i < in1Len; i++) { if (i > outPosition) break; j = outPosition - i; if (j >= in2Len) continue; *result += in1[i] * in2[j]; } } The problem is, using convolveHelper slows down the code about 3.5 times (when running on a single thread). Any ideas on how I can speed-up convolveHelper, while maintaining thread safety?

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  • How to optimize this MYSQL table?

    - by Lost_in_code
    This is for an upcoming project. I have two tables - first one keeps tracks of photos, and the second one keeps track of the photo's rank Photos: +-------+-----------+------------------+ | id | photo | current_rank | +-------+-----------+------------------+ | 1 | apple | 5 | | 2 | orange | 9 | +-------+-----------+------------------+ The photo rank keeps changing on a regular basis and this is the table that tracks it: Ranks: +-------+-----------+----------+-------------+ | id | photo_id | ranks | timestamp | +-------+-----------+----------+-------------+ | 1 | 1 | 8 | * | | 2 | 2 | 2 | * | | 3 | 1 | 3 | * | | 4 | 1 | 7 | * | | 5 | 1 | 5 | * | | 6 | 2 | 9 | * | +-------+-----------+----------+-------------+ * = current timestamp Every rank is tracked for reporting/analysis purpose. I talked to someone who has experience in this field and he told me that storing ranks like above is the way to go. But I'm not so sure yet. The problem here is data redundancy. There are going to be tens of thousands of photos. The photo rank changes on a hourly basis (many time within minutes) for recent photos but less frequently for older photos. At this rate the table will have millions of records within months. And since I do not have experience in working with large databases, this makes me a little nervous. I thought of this: Ranks: +-------+-----------+--------------------+ | id | photo_id | ranks | +-------+-----------+--------------------+ | 1 | 1 | 8:*,3:*,7:*,5:* | | 2 | 2 | 2:*,9:* | +-------+-----------+--------------------+ * = current timestamp That means some extra code in PHP to split the rank/time (and sorting) but that looks OK to me. Is this a correct way to optimize the table for performance? What would you recommend? Any suggestions would be great.

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  • Add Embebded HTML Code withut rendering on HTML Email

    - by Suneth Kalhara
    I creating HTML email but i need to send some html code without rendering (because this code for user he can copy and paste the code on there website) i need to send this code without rendering on html email, i tried code and pre tags but no luck <a href="###"><img src="####" width="300" height="250" border="0" alt="####/><br />Watch Local Cam</a> is there any way to do this

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  • Do you have any tips for commenting code?

    - by Rob Wells
    G'day, I've read both of Steve McConnell's excellent Code Complete books "Code Complete" and "Code Complete 2" and was wondering if people have any other suggestions for commenting code.co My commenting mantra could be summed up by the basic idea of expressing "what the code below cannot say". While enjoying this interesting blog post by Jeff about commenting I was still left wondering "When coding, when do you feel a comment is required?"

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  • Permutations of Varying Size

    - by waiwai933
    I'm trying to write a function in PHP that gets all permutations of all possible sizes. I think an example would be the best way to start off: $my_array = array(1,1,2,3); Possible permutations of varying size: 1 1 // * See Note 2 3 1,1 1,2 1,3 // And so forth, for all the sets of size 2 1,1,2 1,1,3 1,2,1 // And so forth, for all the sets of size 3 1,1,2,3 1,1,3,2 // And so forth, for all the sets of size 4 Note: I don't care if there's a duplicate or not. For the purposes of this example, all future duplicates have been omitted. What I have so far in PHP: function getPermutations($my_array){ $permutation_length = 1; $keep_going = true; while($keep_going){ while($there_are_still_permutations_with_this_length){ // Generate the next permutation and return it into an array // Of course, the actual important part of the code is what I'm having trouble with. } $permutation_length++; if($permutation_length>count($my_array)){ $keep_going = false; } else{ $keep_going = true; } } return $return_array; } The closest thing I can think of is shuffling the array, picking the first n elements, seeing if it's already in the results array, and if it's not, add it in, and then stop when there are mathematically no more possible permutations for that length. But it's ugly and resource-inefficient. Any pseudocode algorithms would be greatly appreciated. Also, for super-duper (worthless) bonus points, is there a way to get just 1 permutation with the function but make it so that it doesn't have to recalculate all previous permutations to get the next? For example, I pass it a parameter 3, which means it's already done 3 permutations, and it just generates number 4 without redoing the previous 3? (Passing it the parameter is not necessary, it could keep track in a global or static). The reason I ask this is because as the array grows, so does the number of possible combinations. Suffice it to say that one small data set with only a dozen elements grows quickly into the trillions of possible combinations and I don't want to task PHP with holding trillions of permutations in its memory at once.

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  • Did anyone create the Java Code Formatter Profile for Eclipse IDE that conforms to the Android Code

    - by yvolk
    Android Code Style Guide defines "Android Code Style Rules". To conform to these rules one have to change quite a number of settings of the Java Code Formatter (Window-Preferences-Java-Formatter) default profile (in Eclipse IDE). Did anyone managed to configure the formatter to follow the "Android Code Style Rules" already? If yes, please export the Formatter profile and publish to be used by community. PS: I've tried to do this myself but I've found that there are too many formatter options available, and most of them are not mentioned in the Code Style Guide :-(

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  • running code if try statements were successful in python

    - by None
    I was wondering if in python there was a simple way to run code if a try statement was successful that wasn't in the try statement itself. Is that what the else or finally commands do (I didn't understand their documentation)? I know I could use code like this: successful = False try: #code that might fail successful = True except: #error handling if code failed if successful: #code to run if try was successful that isn't part of try but I was wondering if there was a shorter way .

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  • Google Translate translates Javascript Code

    - by Matt
    Hi, I have some PHP code that sends a section of html code including some inline Javascript code by curl to google. When i get it back from Google translated into the language that i chose, the Javascript code has been translated too. Any ideas as to how i can stop Google translating my inline JavaScript code? Thanks, M

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  • problems with chili source code highlighter (mysql)

    - by jason
    I am using Chili source code highlighter it works fine with php source using php as the class. But when i change it to mysql it doesnt highlight any SQL code i also tried sql as the classname, i double checked the recipes' and there is a mysql recipes in there. ... What could i be doing wrong? <pre><code id="code" class="php"></code></pre>

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  • Can my loop be optimized any more? (C++)

    - by Sagekilla
    Below is one of my inner loops that's run several thousand times, with input sizes of 20 - 1000 or more. Is there anything I can do to help squeeze any more performance out of this? I'm not looking to move this code to something like using tree codes (Barnes-Hut), but towards optimizing the actual calculations happening inside, since the same calculations occur in the Barnes-Hut algorithm. Any help is appreciated! typedef double real; struct Particle { Vector pos, vel, acc, jerk; Vector oldPos, oldVel, oldAcc, oldJerk; real mass; }; class Vector { private: real vec[3]; public: // Operators defined here }; real Gravity::interact(Particle *p, size_t numParticles) { PROFILE_FUNC(); real tau_q = 1e300; for (size_t i = 0; i < numParticles; i++) { p[i].jerk = 0; p[i].acc = 0; } for (size_t i = 0; i < numParticles; i++) { for (size_t j = i+1; j < numParticles; j++) { Vector r = p[j].pos - p[i].pos; Vector v = p[j].vel - p[i].vel; real r2 = lengthsq(r); real v2 = lengthsq(v); // Calculate inverse of |r|^3 real r3i = Constants::G * pow(r2, -1.5); // da = r / |r|^3 // dj = (v / |r|^3 - 3 * (r . v) * r / |r|^5 Vector da = r * r3i; Vector dj = (v - r * (3 * dot(r, v) / r2)) * r3i; // Calculate new acceleration and jerk p[i].acc += da * p[j].mass; p[i].jerk += dj * p[j].mass; p[j].acc -= da * p[i].mass; p[j].jerk -= dj * p[i].mass; // Collision estimation // Metric 1) tau = |r|^2 / |a(j) - a(i)| // Metric 2) tau = |r|^4 / |v|^4 real mij = p[i].mass + p[j].mass; real tau_est_q1 = r2 / (lengthsq(da) * mij * mij); real tau_est_q2 = (r2*r2) / (v2*v2); if (tau_est_q1 < tau_q) tau_q = tau_est_q1; if (tau_est_q2 < tau_q) tau_q = tau_est_q2; } } return sqrt(sqrt(tau_q)); }

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  • Google Translate translates inline Javascript Code

    - by Matt
    Hi, I have some PHP code that sends a section of html code including some inline Javascript code by curl to google. When i get it back from Google translated into the language that i chose, the Javascript code has been translated too. Any ideas as to how i can stop Google translating my inline JavaScript code? Thanks, M

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  • Do you keep a code bank?

    - by calico-cat
    I've done consulting work for years and I've got code snippets in various languages lying around that I'll re-use for various projects. The collection is getting pretty large and I want to set up a code bank for myself. What code banks do people use? Do you find it helps, or is there some better way of organising my reusable code snippets? (If one does exist, I'd prefer it be open-source, accessible via a web browser, language-agnostic, and maybe colour the code the way Stackoverflow does :)

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  • how to find copyright code???

    - by micheal
    hi all, we were maintaining an MS Access application. Person who actually developed the application used copyrighted code. Now we want to remove that code and re-write that logic. Problem is we dont know what is the copyrighted code and what is not. Is there any way or tool that can be used to scan through the existing code and flag the code that was directly got from internet and used? Thanks in advance.

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  • Optimizing Vector elements swaps using CUDA

    - by Orion Nebula
    Hi all, Since I am new to cuda .. I need your kind help I have this long vector, for each group of 24 elements, I need to do the following: for the first 12 elements, the even numbered elements are multiplied by -1, for the second 12 elements, the odd numbered elements are multiplied by -1 then the following swap takes place: Graph: because I don't yet have enough points, I couldn't post the image so here it is: http://www.freeimagehosting.net/image.php?e4b88fb666.png I have written this piece of code, and wonder if you could help me further optimize it to solve for divergence or bank conflicts .. //subvector is a multiple of 24, Mds and Nds are shared memory _shared_ double Mds[subVector]; _shared_ double Nds[subVector]; int tx = threadIdx.x; int tx_mod = tx ^ 0x0001; int basex = __umul24(blockDim.x, blockIdx.x); Mds[tx] = M.elements[basex + tx]; __syncthreads(); // flip the signs if (tx < (tx/24)*24 + 12) { //if < 12 and even if ((tx & 0x0001)==0) Mds[tx] = -Mds[tx]; } else if (tx < (tx/24)*24 + 24) { //if >12 and < 24 and odd if ((tx & 0x0001)==1) Mds[tx] = -Mds[tx]; } __syncthreads(); if (tx < (tx/24)*24 + 6) { //for the first 6 elements .. swap with last six in the 24elements group (see graph) Nds[tx] = Mds[tx_mod + 18]; Mds [tx_mod + 18] = Mds [tx]; Mds[tx] = Nds[tx]; } else if (tx < (tx/24)*24 + 12) { // for the second 6 elements .. swp with next adjacent group (see graph) Nds[tx] = Mds[tx_mod + 6]; Mds [tx_mod + 6] = Mds [tx]; Mds[tx] = Nds[tx]; } __syncthreads(); Thanks in advance ..

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  • Static code analysis tools

    - by Anil Namde
    Whether JavaSript, C# or C++ main problem i face while reading the code is which function is called by which function. This problem is big when dealing with BIG code. Is there any static code analysis tool/technique/plugins using which a graphical representation of the code can be generated(something like below) so that reading/analyzing code becomes easy? .... --outerFuntion() ---innerFunction() ----innerFunction2() --outerFunction2() .... Please provide your inputs/opinions on this Thanks all,

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  • Please suggest ASP.Net source editor

    - by Jerry
    Can someone suggest ASP.Net source editor which I can integrate into my web site expected features: Highlight ASP.Net source code, including server code / javascript code / html / css Intelligent suggesting when typing the code. (this is optional) "Design View" is not required. I just need the code view, please suggest, thank you

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  • Rewrite code from Threads to AnyEvent

    - by user1779868
    I wrote a code: use LWP::UserAgent; use HTTP::Cookies; use threads; use threads::shared; $| = 1; $threads = 50; my @urls : shared = loadf('url.txt'); my @thread_list = (); $thread_list[$_] = threads->create(\&thread) for 0 .. $threads - 1; $_->join for @thread_list; thread(); sub thread { my ($web, $ck) = browser(); while(1) { my $url = shift @urls; if(!$url) { last; } $code = $web->get($url)->code; print "[+] $url - code: $code\n"; if($code == 200) { open F, ">>200.txt"; print F $url."\n"; close F; } elsif($code == 301) { open F, ">>301.txt"; print F $url."\n"; close F; } else { open F, ">>else.txt"; print F "$url code - $code\n"; close F; } } } sub loadf { open (F, "<".$_[0]) or erroropen($_[0]); chomp(my @data = <F>); close F; return @data; } sub browser { my $web = new LWP::UserAgent; my $ck = new HTTP::Cookies; $web->cookie_jar($ck); $web->agent('Opera/9.80 (Windows 7; U; en) Presto/2.9.168 Version/11.50'); $web->timeout(5); return $web, $ck; } After its working for some time physical storage is full. Can u help me to re-write it with AnyEvent. I tried but my code didn't work. I read that it will help me to safe some memory. Thanks a lot to any helpers.

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  • Optimizing sparse dot-product in C#

    - by Haggai
    Hello. I'm trying to calculate the dot-product of two very sparse associative arrays. The arrays contain an ID and a value, so the calculation should be done only on those IDs that are common to both arrays, e.g. <(1, 0.5), (3, 0.7), (12, 1.3) * <(2, 0.4), (3, 2.3), (12, 4.7) = 0.7*2.3 + 1.3*4.7 . My implementation (call it dict) currently uses Dictionaries, but it is too slow to my taste. double dot_product(IDictionary<int, double> arr1, IDictionary<int, double> arr2) { double res = 0; double val2; foreach (KeyValuePair<int, double> p in arr1) if (arr2.TryGetValue(p.Key, out val2)) res += p.Value * val2; return res; } The full arrays have about 500,000 entries each, while the sparse ones are only tens to hundreds entries each. I did some experiments with toy versions of dot products. First I tried to multiply just two double arrays to see the ultimate speed I can get (let's call this "flat"). Then I tried to change the implementation of the associative array multiplication using an int[] ID array and a double[] values array, walking together on both ID arrays and multiplying when they are equal (let's call this "double"). I then tried to run all three versions with debug or release, with F5 or Ctrl-F5. The results are as follows: debug F5: dict: 5.29s double: 4.18s (79% of dict) flat: 0.99s (19% of dict, 24% of double) debug ^F5: dict: 5.23s double: 4.19s (80% of dict) flat: 0.98s (19% of dict, 23% of double) release F5: dict: 5.29s double: 3.08s (58% of dict) flat: 0.81s (15% of dict, 26% of double) release ^F5: dict: 4.62s double: 1.22s (26% of dict) flat: 0.29s ( 6% of dict, 24% of double) I don't understand these results. Why isn't the dictionary version optimized in release F5 as do the double and flat versions? Why is it only slightly optimized in the release ^F5 version while the other two are heavily optimized? Also, since converting my code into the "double" scheme would mean lots of work - do you have any suggestions how to optimize the dictionary one? Thanks! Haggai

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  • Calculating Growth-Rates by applying log-differences

    - by mropa
    I am trying to transform my data.frame by calculating the log-differences of each column and controlling for the rows id. So basically I like to calculate the growth rates for each id's variable. So here is a random df with an id column, a time period colum p and three variable columns: df <- data.frame (id = c("a","a","a","c","c","d","d","d","d","d"), p = c(1,2,3,1,2,1,2,3,4,5), var1 = rnorm(10, 5), var2 = rnorm(10, 5), var3 = rnorm(10, 5) ) df id p var1 var2 var3 1 a 1 5.375797 4.110324 5.773473 2 a 2 4.574700 6.541862 6.116153 3 a 3 3.029428 4.931924 5.631847 4 c 1 5.375855 4.181034 5.756510 5 c 2 5.067131 6.053009 6.746442 6 d 1 3.846438 4.515268 6.920389 7 d 2 4.910792 5.525340 4.625942 8 d 3 6.410238 5.138040 7.404533 9 d 4 4.637469 3.522542 3.661668 10 d 5 5.519138 4.599829 5.566892 Now I have written a function which does exactly what I want BUT I had to take a detour which is possibly unnecessary and can be removed. However, somehow I am not able to locate the shortcut. Here is the function and the output for the posted data frame: fct.logDiff <- function (df) { df.log <- dlply (df, "code", function(x) data.frame (p = x$p, log(x[, -c(1,2)]))) list.nalog <- llply (df.log, function(x) data.frame (p = x$p, rbind(NA, sapply(x[,-1], diff)))) ldply (list.nalog, data.frame) } fct.logDiff(df) id p var1 var2 var3 1 a 1 NA NA NA 2 a 2 -0.16136569 0.46472004 0.05765945 3 a 3 -0.41216720 -0.28249264 -0.08249587 4 c 1 NA NA NA 5 c 2 -0.05914281 0.36999681 0.15868378 6 d 1 NA NA NA 7 d 2 0.24428771 0.20188025 -0.40279188 8 d 3 0.26646102 -0.07267311 0.47041227 9 d 4 -0.32372771 -0.37748866 -0.70417351 10 d 5 0.17405309 0.26683625 0.41891802 The trouble is due to the added NA-rows. I don't want to collapse the frame and reduce it, which would be automatically done by the diff() function. So I had 10 rows in my original frame and am keeping the same amount of rows after the transformation. In order to keep the same length I had to add some NAs. I have taken a detour by transforming the data.frame into a list, add the NAs, and afterwards transform the list back into a data.frame. That looks tedious. Any ideas to avoid the data.frame-list-data.frame class transformation and optimize the function?

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  • How do I branch if message.properties-code exists

    - by skurt
    I want to branch if a message-property-code does exist or not. <g:if test="${message(code: 'default.code.foo')}"> true </g:if><g:else> false </g:else> should answer true if there a message property named default.code.foo and false if not. It fails because it answers the code if there is no property for it.

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  • Did anyone created the Java Code Formatter Profile for Eclipse IDE that conforms to the Android Code

    - by yvolk
    Android Code Style Guide defines "Android Code Style Rules". To conform to these rules one have to change quite a number of settings of the Java Code Formatter (Window-Preferences-Java-Formatter) default profile (in Eclipse IDE). Did anyone managed to configure the formatter to follow the "Android Code Style Rules" already? PS: I've tried to do this myself but I've found that there are too many formatter options available, and most of them are not mentioned in the Code Style Guide :-(

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