Search Results

Search found 90546 results on 3622 pages for 'code optimization'.

Page 144/3622 | < Previous Page | 140 141 142 143 144 145 146 147 148 149 150 151  | Next Page >

• What is the most platform- and Python-version-independent way to make a fast loop for use in Python?

  - by Statto

  I'm writing a scientific application in Python with a very processor-intensive loop at its core. I would like to optimise this as far as possible, at minimum inconvenience to end users, who will probably use it as an uncompiled collection of Python scripts, and will be using Windows, Mac, and (mainly Ubuntu) Linux. It is currently written in Python with a dash of NumPy, and I've included the code below. Is there a solution which would be reasonably fast which would not require compilation? This would seem to be the easiest way to maintain platform-independence. If using something like Pyrex, which does require compilation, is there an easy way to bundle many modules and have Python choose between them depending on detected OS and Python version? Is there an easy way to build the collection of modules without needing access to every system with every version of Python? Does one method lend itself particularly to multi-processor optimisation? (If you're interested, the loop is to calculate the magnetic field at a given point inside a crystal by adding together the contributions of a large number of nearby magnetic ions, treated as tiny bar magnets. Basically, a massive sum of these.) # calculate_dipole # ------------------------- # calculate_dipole works out the dipole field at a given point within the crystal unit cell # --- # INPUT # mu = position at which to calculate the dipole field # r_i = array of atomic positions # mom_i = corresponding array of magnetic moments # --- # OUTPUT # B = the B-field at this point def calculate_dipole(mu, r_i, mom_i): relative = mu - r_i r_unit = unit_vectors(relative) #4pi / mu0 (at the front of the dipole eqn) A = 1e-7 #initalise dipole field B = zeros(3,float) for i in range(len(relative)): #work out the dipole field and add it to the estimate so far B += A*(3*dot(mom_i[i],r_unit[i])*r_unit[i] - mom_i[i]) / sqrt(dot(relative[i],relative[i]))**3 return B

  Read the article

• Linux PDF/Postscript Optimizing

  - by Sheldon Ross

  So I have a report system built using Java and iText. PDF templates are created using Scribus. The Java code merges the data into the document using iText. The files are then copied over to a NFS share, and a BASH script prints them. I use acroread to convert them to PS, then lpr the PS. The FOSS application pdftops is horribly inefficient. My main problem is that the PDF's generated using iText/Scribus are very large. And I've recently run into the problem where acroread pukes because it hits 4gb of mem usage on large (300+ pages) documents. (Adobe is painfully slow at updating stuff to 64 bit). Now I can use Adobe reader on Windows, and use the Create Print PDF option or whatever its called, and it greatly( 10x) reduces the size of the PDF(it removes alot of metadata about form fields and such it appears) and produces a PDF that is basically a Print image. My question is does anyone know of a good solution/program for doing something similiar on Linux. Ideally, it would optimize the PDF, reduce size, and reduce PS complexity so the printer could print faster as it takes about 15-20 seconds a page to print right now.

  Read the article

• Two strange efficiency problems in Mathematica

  - by Jess Riedel

  FIRST PROBLEM I have timed how long it takes to compute the following statements (where V[x] is a time-intensive function call): Alice = Table[V[i],{i,1,300},{1000}]; Bob = Table[Table[V[i],{i,1,300}],{1000}]^tr; Chris_pre = Table[V[i],{i,1,300}]; Chris = Table[Chris_pre,{1000}]^tr; Alice, Bob, and Chris are identical matricies computed 3 slightly different ways. I find that Chris is computed 1000 times faster than Alice and Bob. It is not surprising that Alice is computed 1000 times slower because, naively, the function V must be called 1000 more times than when Chris is computed. But it is very surprising that Bob is so slow, since he is computed identically to Chris except that Chris stores the intermediate step Chris_pre. Why does Bob evaluate so slowly? SECOND PROBLEM Suppose I want to compile a function in Mathematica of the form f(x)=x+y where "y" is a constant fixed at compile time (but which I prefer not to directly replace in the code with its numerical because I want to be able to easily change it). If y's actual value is y=7.3, and I define f1=Compile[{x},x+y] f2=Compile[{x},x+7.3] then f1 runs 50% slower than f2. How do I make Mathematica replace "y" with "7.3" when f1 is compiled, so that f1 runs as fast as f2? Many thanks!

  Read the article

• Problem with closing excel by c#

  - by phenevo

  Hi, I've got unit test with this code: Excel.Application objExcel = new Excel.Application(); Excel.Workbook objWorkbook = (Excel.Workbook)(objExcel.Workbooks._Open(@"D:\Selenium\wszystkieSeba2.xls", true, false, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value)); Excel.Worksheet ws = (Excel.Worksheet)objWorkbook.Sheets[1]; Excel.Range r = ws.get_Range("A1", "I2575"); DateTime dt = DateTime.Now; Excel.Range cellData = null; Excel.Range cellKwota = null; string cellValueData = null; string cellValueKwota = null; double dataTransakcji = 0; string dzien = null; string miesiac = null; int nrOperacji = 1; int wierszPoczatkowy = 11; int pozostalo = 526; cellData = r.Cells[wierszPoczatkowy, 1] as Excel.Range; cellKwota = r.Cells[wierszPoczatkowy, 6] as Excel.Range; if ((cellData != null) && (cellKwota != null)) { object valData = cellData.Value2; object valKwota = cellKwota.Value2; if ((valData != null) && (valKwota != null)) { cellValueData = valData.ToString(); dataTransakcji = Convert.ToDouble(cellValueData); Console.WriteLine("data transakcji to: " + dataTransakcji); dt = DateTime.FromOADate((double)dataTransakcji); dzien = dt.Day.ToString(); miesiac = dt.Month.ToString(); cellValueKwota = valKwota.ToString(); } } r.Cells[wierszPoczatkowy, 8] = "ok"; objWorkbook.Save(); objWorkbook.Close(true, @"C:\Documents and Settings\Administrator\Pulpit\Selenium\wszystkieSeba2.xls", true); objExcel.Quit(); Why after finish test I'm still having excel in process (it does'nt close) And : is there something I can improve to better perfomance ??

  Read the article

• Optimizing PHP require_once's for low disk i/o?

  - by buggedcom

  Q1) I'm designing a CMS (-who isn't!) but priority is being given to caching. Literally everything is cached. DB rows, DB id queries, Configuration data, processed data, compiled templates. Currently it has two layers of caching. The first is a opcode cache or memory cache such as apc, eaccelerator, xcache or memcached. If an entry is not found in there it is then searched for in the secondary slow cache, ie php includes. Are the opcode caches actually faster than doing a require_once to a php file with a var_export'd array of data in it? My tests are inconclusive as my development box (5.3 of XAMPP) keeps throwing errors installing any of the aforementioned programs. Q2) The CMS has numerous helper classes that are autoloaded on demand instead of loading all files. Mostly each has a require before it so no autoloading needs to take place, however this is not the question. Because a page script can have up to 50/60 helper files included I have a feeling that if the site was under pressure it would buckle because of all the i/o that this incurs. Ignore for the moment that there is output cache in place that would remove the need for what I am about to suggest, and also that opcode caches would render this moot. What I have tried to do is join all the helper files required for the scripts execution in one single file. This is achievable and works well, however it has a side effect of greatly increasing the memory usage dramatically even though technically the same code is being used. What are your thoughts and opinions on this?

  Read the article

• When optimizing database queries, what exactly is the relationship between number of queries and siz

  - by williamjones

  To optimize application speed, everyone always advises to minimize the number of queries an application makes to the database, consolidating them into fewer queries that retrieve more wherever possible. However, this also always comes with the caution that data transferred is still data transferred, and just because you are making fewer queries doesn't make the data transferred free. I'm in a situation where I can over-include on the query in order to cut down the number of queries, and simply remove the unwanted data in the application code. Is there any type of a rule of thumb on how much of a cost there is to each query, to know when to optimize number of queries versus size of queries? I've tried to Google for objective performance analysis data, but surprisingly haven't been able to find anything like that. Clearly this relationship will change for factors such as when the database grows in size, making this somewhat individualized, but surely this is not so individualized that a broad sense of the landscape can't be drawn out? I'm looking for general answers, but for what it's worth, I'm running an application on Heroku.com, which means Ruby on Rails with a Postgres database.

  Read the article

• Datatable add new column and values speed issue

  - by Cine

  I am having some speed issue with my datatables. In this particular case I am using it as holder of data, it is never used in GUI or any other scenario that actually uses any of the fancy features. In my speed trace, this particular constructor was showing up as a heavy user of time when my database is ~40k rows. The main user was set_Item of DataTable. protected myclass(DataTable dataTable, DataColumn idColumn) { this.dataTable = dataTable; IdColumn = idColumn ?? this.dataTable.Columns.Add(string.Format("SYS_{0}_SYS", Guid.NewGuid()), Type.GetType("System.Int32")); JobIdColumn = this.dataTable.Columns.Add(string.Format("SYS_{0}_SYS", Guid.NewGuid()), Type.GetType("System.Int32")); IsNewColumn = this.dataTable.Columns.Add(string.Format("SYS_{0}_SYS", Guid.NewGuid()), Type.GetType("System.Int32")); int id = 1; foreach (DataRow r in this.dataTable.Rows) { r[JobIdColumn] = id++; r[IsNewColumn] = (r[IdColumn] == null || r[IdColumn].ToString() == string.Empty) ? 1 : 0; } Digging deeper into the trace, it turns out that set_Item calls EndEdit, which brings my thoughts to the transaction support of the DataTable, for which I have no usage for in my scenario. So my solution to this was to open editing on all of the rows and never close them again. _dt.BeginLoadData(); foreach (DataRow row in _dt.Rows) row.BeginEdit(); Is there a better solution? This feels too much like a big giant hack that will eventually come and bite me. You might suggest that I dont use DataTable at all, but I have already considered that and rejected it due to the amount of effort that would be required to reimplement with a custom class. The main reason it is a datatable is that it is ancient code (.net 1.1 time) and I dont want to spend that much time changing it, and it is also because the original table comes out of a third party component.

  Read the article

• Shouldn't prepared statements be much faster?

  - by silversky

  $s = explode (" ", microtime()); $s = $s[0]+$s[1]; $con = mysqli_connect ('localhost', 'test', 'pass', 'db') or die('Err'); for ($i=0; $i<1000; $i++) { $stmt = $con -> prepare( " SELECT MAX(id) AS max_id , MIN(id) AS min_id FROM tb "); $stmt -> execute(); $stmt->bind_result($M,$m); $stmt->free_result(); $rand = mt_rand( $m , $M ).'<br/>'; $res = $con -> prepare( " SELECT * FROM tb WHERE id >= ? LIMIT 0,1 "); $res -> bind_param("s", $rand); $res -> execute(); $res->free_result(); } $e = explode (" ", microtime()); $e = $e[0]+$e[1]; echo number_format($e-$s, 4, '.', ''); // and: $link = mysql_connect ("localhost", "test", "pass") or die (); mysql_select_db ("db") or die ("Unable to select database".mysql_error()); for ($i=0; $i<1000; $i++) { $range_result = mysql_query( " SELECT MAX(`id`) AS max_id , MIN(`id`) AS min_id FROM tb "); $range_row = mysql_fetch_object( $range_result ); $random = mt_rand( $range_row->min_id , $range_row->max_id ); $result = mysql_query( " SELECT * FROM tb WHERE id >= $random LIMIT 0,1 "); } defenitly prepared statements are much more safer but also every where it says that they are much faster BUT in my test on the above code I have: - 2.45 sec for prepared statements - 5.05 sec for the secon example What do you think I'm doing wrong? Should I use the second solution or I should try to optimize the prep stmt?

  Read the article

• PHP Hashtable array optimisation.

  - by hiprakhar

  I made a PHP app which was taking about ~0.0070sec for execution. Now, I added a hashtable array with about 2000 values. Suddenly the time for execution has gone up to ~0.0700 secs. Almost 10 times the previous value. I tried commenting out the part where I was searching inside the hashtable array (but array was still left defined). Still, the execution time remains about ~0.0500secs. Array is something like: $subjectinfo = array( 'TPT753' => 'Industrial Training', 'TPT801' => 'High Polymeric Engineering', 'TPT802' => 'Corrosion Engineering', 'TPT803' => 'Decorative ,Industrial And High Performance Coatings', 'TPT851' => 'Project'); Is there any way to optimize this part? I cannot use Database as I am running this app on Google app engine which is still not supporting JDO database for php. Some more code from the app: function getsubjectinfo($name) { $subjectinfo = array( 'TPT753' => 'Industrial Training', 'TPT801' => 'High Polymeric Engineering', 'TPT802' => 'Corrosion Engineering', 'TPT803' => 'Decorative ,Industrial And High Performance Coatings', 'TPT851' => 'Project'); $name = str_replace("-", "", $name); $name = str_replace(" ", "", $name); if (isset($subjectinfo["$name"])) return "(".$subjectinfo["$name"].")"; else return ""; } Then I am using the following statement 2-3 times in the app: echo $key." ".$this->getsubjectinfo($key)

  Read the article

• How does loop address alignment affect the speed on Intel x86_64?

  - by Alexander Gololobov

  I'm seeing 15% performance degradation of the same C++ code compiled to exactly same machine instructions but located on differently aligned addresses. When my tiny main loop starts at 0x415220 it's faster then when it is at 0x415250. I'm running this on Intel Core2 Duo. I use gcc 4.4.5 on x86_64 Ubuntu. Can anybody explain the cause of slowdown and how I can force gcc to optimally align the loop? Here is the disassembly for both cases with profiler annotation: 415220 576 12.56% |XXXXXXXXXXXXXX 48 c1 eb 08 shr $0x8,%rbx 415224 110 2.40% |XX 0f b6 c3 movzbl %bl,%eax 415227 0.00% | 41 0f b6 04 00 movzbl (%r8,%rax,1),%eax 41522c 40 0.87% | 48 8b 04 c1 mov (%rcx,%rax,8),%rax 415230 806 17.58% |XXXXXXXXXXXXXXXXXXX 4c 63 f8 movslq %eax,%r15 415233 186 4.06% |XXXX 48 c1 e8 20 shr $0x20,%rax 415237 102 2.22% |XX 4c 01 f9 add %r15,%rcx 41523a 414 9.03% |XXXXXXXXXX a8 0f test $0xf,%al 41523c 680 14.83% |XXXXXXXXXXXXXXXX 74 45 je 415283 ::Run(char const*, char const*)+0x4b3 41523e 0.00% | 41 89 c7 mov %eax,%r15d 415241 0.00% | 41 83 e7 01 and $0x1,%r15d 415245 0.00% | 41 83 ff 01 cmp $0x1,%r15d 415249 0.00% | 41 89 c7 mov %eax,%r15d 415250 679 13.05% |XXXXXXXXXXXXXXXX 48 c1 eb 08 shr $0x8,%rbx 415254 124 2.38% |XX 0f b6 c3 movzbl %bl,%eax 415257 0.00% | 41 0f b6 04 00 movzbl (%r8,%rax,1),%eax 41525c 43 0.83% |X 48 8b 04 c1 mov (%rcx,%rax,8),%rax 415260 828 15.91% |XXXXXXXXXXXXXXXXXXX 4c 63 f8 movslq %eax,%r15 415263 388 7.46% |XXXXXXXXX 48 c1 e8 20 shr $0x20,%rax 415267 141 2.71% |XXX 4c 01 f9 add %r15,%rcx 41526a 634 12.18% |XXXXXXXXXXXXXXX a8 0f test $0xf,%al 41526c 749 14.39% |XXXXXXXXXXXXXXXXXX 74 45 je 4152b3 ::Run(char const*, char const*)+0x4c3 41526e 0.00% | 41 89 c7 mov %eax,%r15d 415271 0.00% | 41 83 e7 01 and $0x1,%r15d 415275 0.00% | 41 83 ff 01 cmp $0x1,%r15d 415279 0.00% | 41 89 c7 mov %eax,%r15d

  Read the article

• When to use certain optimizations such as -fwhole-program and -fprofile-generate with several shared libraries

  - by James

  Probably a simple answer; I get quite confused with the language used in the GCC documentation for some of these flags! Anyway, I have three libraries and a programme which uses all these three. I compile each of my libraries seperately with individual (potentially) different sets of warning flags. However, I compile all three libraries with the same set of optimisation flags. I then compile my main programme linking in these three libraries with its own set of warning flags and the same optimisation flags used during the libraries' compilation. 1) Do I have to compile the libraries with optimisation flags present or can I just use these flags when compiling the final programme and linking to the libraries? If the latter, will it then optimise all or just some (presumably that which is called) of the code in these libraries? 2) I would like to use -fwhole-program -flto -fuse-linker-plugin and the linker plugin gold. At which stage do I compile with these on ... just the final compilation or do these flags need to be present during the compilation of the libraries? 3) Pretty much the same as 2) however with, -fprofile-generate -fprofile-arcs and -fprofile-use. I understand one first runs a programme with generate, and then with use. However, do I have to compile each of the libraries with generate/use etc. or just the final programme? And if it is just the last programme, when I then compeil with -fprofile-use will it also optimise the libraries functionality? Many thanks, James

  Read the article

• How to improve performance of map that loads new overlay images

  - by anthonysomerset

  I have inherited a website to maintain that uses a html map overlaying a real map to link specific countries to specific pages. previously it loaded the default map image, then with some javascript it would change the image src to an image with that particular country in a different colour on mouseover and reset the image source back to the original image on mouse out to make maintenance (adding new countries) easier i made the initial map a background image by utilising some CSS for the div tag, and then created new images for each country which only had that countries hightlight so that the images remain fairly small. this works great but theres one issue which is particularly noticeable on slower internet connections when you hover over a country if you dont have the image file in your browser cache or downloaded it wont load the image unless you hover over another country and then back onto the first country - i guess this is due to the image having to manually be downloaded on first hover. My question: is it possible to force the load of these extra images AFTER the page and all the other assets have finished loading so that this behaviour is all but eliminated? the html code for the MAP is as follows: <div class="gtmap"><img id="Image-Maps_6200909211657061" src="<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png" usemap="#Image-Maps_6200909211657061" alt="We offer Guided Motorcycle Tours all around the world" width="615" height="296" /> <map id="_Image-Maps_6200909211657061" name="Image-Maps_6200909211657061"> <area shape="poly" coords="511,134,532,107,542,113,520,141" href="/guided-motorcycle-tours-japan/" alt="Guided Japan Motorcycle Tours" title="Japan" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-japan.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="252,61,266,58,275,64,262,68" href="/guided-motorcycle-tour.php?iceland-motorcycle-adventure-39" alt="Guided Iceland Motorcycle Tours" title="Iceland" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-iceland.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="587,246,597,256,577,279,568,270" href="/guided-motorcycle-tour.php?new-zealand-south-island-adventure-10" alt="New Zealand Guided Motorcycle Tours" title="New Zealand" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-nz.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="418,133,412,145,412,154,421,178,430,180,430,166,443,154,443,145,438,144,433,142,430,138,431,130,430,129,425,128" href="/guided-motorcycle-tours-india/" alt="India Guided Motorcycle Tours" title="India" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-india.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="460,152,466,149,474,165,470,171,466,161" href="/guided-motorcycle-tours-laos/" alt="Laos Guided Motorcycle Tours" title="Laos" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-laos.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="468,179,475,166,468,152,475,152,482,169" href="/guided-motorcycle-tour.php?indochina-motorcycle-adventure-tour-32" onClick="javascript: pageTracker._trackPageview('/internal-links/guided-tours/map/vietnam');" alt="Vietnam Guided Motorcycle Tours" title="Vietnam" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-viet.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="330,239,337,235,347,226,352,233,351,243,344,250,335,253,327,255,323,249,322,242,323,241" href="/guided-motorcycle-tours-southafrica/" alt="South Africa Guided Motorcycle Tours" title="South Africa" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-sa.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="290,77,293,86,298,96,286,102,285,97,285,89,282,84,282,79" href="/guided-motorcycle-tour.php?great-britain-isle-of-man-scotland-wales-uk-18" alt="United Kingdom" title="United Kingdom Guided Motorcycle Tours" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-uk.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="357,118,368,118,369,126,345,129,338,125,338,117,342,115,348,116" href="/guided-motorcycle-tour.php?explore-turkey-adventure-45" alt="Turkey" title="Turkey Guided Motorcycle Tours" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-turkey.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="206,95,193,101,185,101,178,106,165,111,157,109,147,105,134,103,121,103,107,103,96,103,86,104,81,99,77,91,70,83,62,79,60,72,61,64,59,57,60,51,71,50,83,49,95,50,107,54,117,53,129,47,137,36,148,37,163,38,177,44,187,54,195,60,184,72,191,80,200,87" href="/guided-motorcycle-tours-canada/" alt="Guided Canada Motorcycle Tours" title="Canada" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-canada.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="61,75,60,62,60,55,59,44,51,44,43,43,36,42,28,43,23,48,17,51,15,62,19,74,27,79,19,83,16,93,35,83,43,77,50,75,55,75" href="/guided-motorcycle-tours-alaska/" alt="Guided Alaska Motorcycle Tours" title="Alaska" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-alaska.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="82,101,99,101,133,101,148,105,161,110,172,106,187,100,180,113,171,122,165,131,159,149,147,141,137,140,129,147,120,141,112,138,103,137,93,132,86,122,86,112,86,106" href="/guided-motorcycle-tours-usa/" alt="USA Guided Motorcycle Tours" title="USA" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-usa.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="178,225,180,214,175,208,174,204,178,198,174,193,167,192,157,199,158,204,164,211,167,218" href="/guided-motorcycle-tour.php?peru-machu-picchu-adventure-25" alt="Peru Guided Motorcycle Tours" title="Peru" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-peru.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="172,226,169,239,166,256,166,267,164,279,171,277,174,262,175,250,179,234,180,225,176,224" href="/guided-motorcycle-tours-chile/" alt="Guided Chile Motorcycle Tours" title="Chile" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-chile.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="199,260,194,261,187,265,184,276,183,296,170,292,168,282,174,270,174,257,177,245,180,230,190,228,205,237,199,245" href="/guided-motorcycle-tours-argentina/" alt="Guided Argentina Motorcycle Tours" title="Argentina" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-arg.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> </map> </div> The <?php echo cdnhttpsCheck(); ?> is just a site specific function that gets the correct web domain/url from a config file to load resources from CDN where possible (eg all non HTTPS requests) We are loading Jquery at the bottom of the HTML if anybody wonders why it is missing from the code snippet for reference, the page with the map in question is found here: http://www.motoquest.com/guided-motorcycle-tours/

  Read the article

• unroll nested for loops in C++

  - by Hristo

  How would I unroll the following nested loops? for(k = begin; k != end; ++k) { for(j = 0; j < Emax; ++j) { for(i = 0; i < N; ++i) { if (j >= E[i]) continue; array[k] += foo(i, tr[k][i], ex[j][i]); } } } I tried the following, but my output isn't the same, and it should be: for(k = begin; k != end; ++k) { for(j = 0; j < Emax; ++j) { for(i = 0; i+4 < N; i+=4) { if (j >= E[i]) continue; array[k] += foo(i, tr[k][i], ex[j][i]); array[k] += foo(i+1, tr[k][i+1], ex[j][i+1]); array[k] += foo(i+2, tr[k][i+2], ex[j][i+2]); array[k] += foo(i+3, tr[k][i+3], ex[j][i+3]); } if (i < N) { for (; i < N; ++i) { if (j >= E[i]) continue; array[k] += foo(i, tr[k][i], ex[j][i]); } } } } I will be running this code in parallel using Intel's TBB so that it takes advantage of multiple cores. After this is finished running, another function prints out what is in array[] and right now, with my unrolling, the output isn't identical. Any help is appreciated. Thanks, Hristo

  Read the article

• Will the compiler optimize escaping an inner loop?

  - by BCS

  The code I have looks like this (all uses of done shown): bool done = false; for(int i = 0; i < big; i++) { ... for(int j = 0; j < wow; j++) { ... if(foo(i,j)) { done = true; break; } ... } if(done) break; ... } will any compilers convert it to this: for(int i = 0; i < big; i++) { ... for(int j = 0; j < wow; j++) { ... if(foo(i,j)) goto __done; // same as a labeled break if we had it ... } ... } __done:;

  Read the article

• Cleaner way of using modulus for columns

  - by WmasterJ

  I currently have a list (<ul>) of people that I have divided up into two columns. But after finishing the code for it I keept wondering if there is a more effective or clean way to do the same thing. echo "<table class='area_list'><tr>"; // Loop users within areas, divided up in 2 columns $count = count($areaArray); for($i=0 ; $i<$count ; $i++) { $uid = $areaArray[$i]; // get the modulus value + ceil for uneven numbers $rowCalc = ($i+1) % ceil($count/2); if ($rowCalc == 1) echo "<td><ul>"; // OUTPUT the actual list item echo "<li>{$users[$uid]->profile_lastname}</li>"; if ($rowCalc == 0 && $i!=0) echo "</ul></td>"; } echo "</tr></table>"; Any ideas of how to make this cleaner or do it in another way?

  Read the article

• Is the C++ compiler optimizer allowed to break my destructor ability to be called multiple times?

  - by sharptooth

  We once had an interview with a very experienced C++ developer who couldn't answer the following question: is it necessary to call the base class destructor from the derived class destructor in C++? Obviously the answer is no, C++ will call the base class destructor automagically anyway. But what if we attempt to do the call? As I see it the result will depend on whether the base class destructor can be called twice without invoking erroneous behavior. For example in this case: class BaseSafe { public: ~BaseSafe() { } private: int data; }; class DerivedSafe { public: ~DerivedSafe() { BaseSafe::~BaseSafe(); } }; everything will be fine - the BaseSafe destructor can be called twice safely and the program will run allright. But in this case: class BaseUnsafe { public: BaseUnsafe() { buffer = new char[100]; } ~BaseUnsafe () { delete[] buffer; } private: char* buffer; }; class DerivedUnsafe { public: ~DerivedUnsafe () { BaseUnsafe::~BaseUnsafe(); } }; the explicic call will run fine, but then the implicit (automagic) call to the destructor will trigger double-delete and undefined behavior. Looks like it is easy to avoid the UB in the second case. Just set buffer to null pointer after delete[]. But will this help? I mean the destructor is expected to only be run once on a fully constructed object, so the optimizer could decide that setting buffer to null pointer makes no sense and eliminate that code exposing the program to double-delete. Is the compiler allowed to do that?

  Read the article

• genStrAsCharArray optimisation benefits

  - by Rich

  Hi I am looking into the options available to me for optimising the performance of JBoss 5.1.0. One of the options I am looking at is setting genStrAsCharArray to true in <JBOSS_HOME>/server/<PROFILE>/deployers/jbossweb.deployer/web.xml. This affects the generation of .java code from .JSPs. The comment describes this flag as: Should text strings be generated as char arrays, to improve performance in some cases? I have a few questions about this. Is this the generation of Strings in the dynamic parts of the JSP page (ie each time the page is called) or is it the generation of Strings in the static parts (ie when the .java is built from the JSP)? "in some cases" - which cases are these? What are the situations where the performance is worse? Does this speed up the generation of the .java, the compilation of the .class or the execution of the .class? At a more technical level (and the answer to this will probably depend on the answer to part 1), why can the use of char arrays improve performance? Thanks in advance Rich

  Read the article

• glDrawArrays() slow on iPad?

  - by Nick

  Hey guys, I was wondering how to speed up my iPad application using OpenGLES 2.0. At the moment we have every drawable object draw itself with a call to glDrawArrays(). Blend mode is on, we really need it. Without disabling blendmode, how would we improve performance for this app? For instances, if we now draw 1 texture across the whole screen, the app only gets 15FPS, which is really slow I think? Are we doing something terribly wrong? Our drawing code (for each drawable), is as follows: - (void) draw { GLuint textureAvailable = 0; if(texture != nil){ textureAvailable = 1; } glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture.name); glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, vertices); glEnableVertexAttribArray(ATTRIB_VERTEX); glVertexAttribPointer(ATTRIB_COLOR, 4, GL_FLOAT, 1, 0, colorsWithMultipliedAlpha); glEnableVertexAttribArray(ATTRIB_COLOR); glVertexAttribPointer(ATTRIB_TEXTUREMAP, 2, GL_FLOAT, 1, 0, textureMapping); glEnableVertexAttribArray(ATTRIB_TEXTUREMAP); //Note that we are NOT using position.z here because that is only used to determine drawing order int *jnUniforms = JNOpenGLConstants::getInstance().uniforms; glUniform4f(jnUniforms[UNIFORM_TRANSLATE], position.x, position.y, 0.0, 0.0); glUniform4f(jnUniforms[UNIFORM_SCALE], scale.x, scale.y, 1.0, 1.0); glUniform1f(jnUniforms[UNIFORM_ROTATION], rotation); glUniform1i(jnUniforms[UNIFORM_TEXTURE_SAMPLE], 0); glUniform2f(jnUniforms[UNIFORM_TEXTURE_REPEAT], textureRepeat.x, textureRepeat.y); glUniform1i(jnUniforms[UNIFORM_TEXTURE_AVAILABLE], textureAvailable); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); }

  Read the article

• Fast find object by string property

  - by Andrew Kalashnikov

  Hello, colleagues. I've got task to fast find object by its string property. Object: class DicDomain { public virtual string Id{ get; set; } public virtual string Name { get; set; } } For storing my object I use List[T] dictionary where T is DicDomain for now . I've got 5-10 such lists, which contain about 500-20000 at each one. Task is find objects by its Name. I use next code now: List<T> entities = dictionary.FindAll(s => s.Name.Equals(word, StringComparison.OrdinalIgnoreCase)); I've got some questions: Is my search speed optimal. I think now. Data structure. It List good for this task. What about hashtable,sorted... Method Find. May be i should use string intern?? I haven't much exp at these tasks. Can u give me good advice for increase perfomance. Thanks

  Read the article

• Scalably processing large amount of comlpicated database data in PHP, many times a day.

  - by Eph

  I'm soon to be working on a project that poses a problem for me. It's going to require, at regular intervals throughout the day, processing tens of thousands of records, potentially over a million. Processing is going to involve several (potentially complicated) formulas and the generation of several random factors, writing some new data to a separate table, and updating the original records with some results. This needs to occur for all records, ideally, every three hours. Each new user to the site will be adding between 50 and 500 records that need to be processed in such a fashion, so the number will not be steady. The code hasn't been written, yet, as I'm still in the design process, mostly because of this issue. I know I'm going to need to use cron jobs, but I'm concerned that processing records of this size may cause the site to freeze up, perform slowly, or just piss off my hosting company every three hours. I'd like to know if anyone has any experience or tips on similar subjects? I've never worked at this magnitude before, and for all I know, this will be trivial to the server and not pose much of an issue. As long as ALL records are processed before the next three hour period occurs, I don't care if they aren't processed simultaneously (though, ideally, all records belonging to a specific user should be processed in the same batch), so I've been wondering if I should process in batches every 5 minutes, 15 minutes, hour, whatever works, and how best to approach this (and make it scalable in a way that is fair to all users)?

  Read the article

• Word frequency tally script is too slow

  - by Dave Jarvis

  Background Created a script to count the frequency of words in a plain text file. The script performs the following steps: Count the frequency of words from a corpus. Retain each word in the corpus found in a dictionary. Create a comma-separated file of the frequencies. The script is at: http://pastebin.com/VAZdeKXs Problem The following lines continually cycle through the dictionary to match words: for i in $(awk '{if( $2 ) print $2}' frequency.txt); do grep -m 1 ^$i\$ dictionary.txt >> corpus-lexicon.txt; done It works, but it is slow because it is scanning the words it found to remove any that are not in the dictionary. The code performs this task by scanning the dictionary for every single word. (The -m 1 parameter stops the scan when the match is found.) Question How would you optimize the script so that the dictionary is not scanned from start to finish for every single word? The majority of the words will not be in the dictionary. Thank you!

  Read the article

• MySQL Datefields: duplicate or calculate?

  - by Konerak

  We are using a table with a structure imposed upon us more than 10 years ago. We are allowed to add columns, but urged not to change existing columns. Certain columns are meant to represent dates, but are put in different format. Amongst others: * CHAR(6): YYMMDD * CHAR(6): DDMMYY * CHAR(8): YYYYMMDD * CHAR(8): DDMMYYYY * DATE * DATETIME Since we now would like to do some more complex queries, using advanced date functions, my manager proposed to d*uplicate those problem columns* to a proper FORMATTED_OLDCOLUMNNAME column using a DATE or DATETIME format. Is this the way to go? Couldn't we just use the STR_TO_DATE function each time we accessed the columns? To avoid every query having to copy-paste the function, I could still work with a view or a stored procedure, but duplicating data to avoid recalculation sounds wrong. Solutions I see (I guess I prefer 2.2.1) 1. Physically duplicate columns 1.1 In the same table 1.1.1 Added by each script that does a modification (INSERT/UPDATE/REPLACE/...) 1.1.2 Maintained by a trigger on each modification 1.2 In a separate table 1.2.1 Added by each script that does a modification (INSERT/UPDATE/REPLACE/...) 1.2.2 Maintained by a trigger on each modification 2. On-demand transformation 2.1 Each query has to perform the transformation 2.1.1 Using copy-paste in the source code 2.1.2 Using a library 2.1.3 Using a STORED PROCEDURE 2.2 A view performs the transformation 2.2.1 A separate table replacing the entire table 2.2.2 A separate table just adding the date-fields for the primary keys Am I right to say it's better to recalculate than to store? And would a view be a good solution?

  Read the article

• How to speed-up a simple method (preferably without changing interfaces or data structures)?

  - by baol

  I have some data structures: all_unordered_m is a big vector containing all the strings I need (all different) ordered_m is a small vector containing the indexes of a subset of the strings (all different) in the former vector position_m maps the indexes of objects from the first vector to their position in the second one. The string_after(index, reverse) method returns the string referenced by ordered_m after all_unordered_m[index]. ordered_m is considered circular, and is explored in natural or reverse order depending on the second parameter. The code is something like the following: struct ordered_subset { // [...] std::vector<std::string>& all_unordered_m; // size = n >> 1 std::vector<size_t> ordered_m; // size << n std::tr1::unordered_map<size_t, size_t> position_m; const std::string& string_after(size_t index, bool reverse) const { size_t pos = position_m.find(index)->second; if(reverse) pos = (pos == 0 ? orderd_m.size() - 1 : pos - 1); else pos = (pos == ordered.size() - 1 ? 0 : pos + 1); return all_unordered_m[ordered_m[pos]]; } }; Given that: I do need all of the data-structures for other purposes; I cannot change them because I need to access the strings: by their id in the all_unordered_m; by their index inside the various ordered_m; I need to know the position of a string (identified by it's position in the first vector) inside ordered_m vector; I cannot change the string_after interface without changing most of the program. How can I speed up the string_after method that is called billions of times and is eating up about 10% of the execution time?

  Read the article

• How to speed-up a simple method? (possibily without changing interfaces or data structures)

  - by baol

  Hello. I have some data structures: all_unordered_mordered_m is a big vector containing all the strings I need (all different) ordered_m is a small vector containing the indexes of a subset of the strings (all different) in the former vector position_m maps the indexes of objects from the first vector to their position in the second one. The string_after(index, reverse) method returns the string referenced by ordered_m after all_unordered_m[index]. ordered_m is considered circular, and is explored in natural or reverse order depending on the second parameter. The code is something like the following: struct ordered_subset { // [...] std::vector<std::string>& all_unordered_m; // size = n >> 1 std::vector<size_t> ordered_m; // size << n std::map<size_t, size_t> position_m; // positions of strings in ordered_m const std::string& string_after(size_t index, bool reverse) const { size_t pos = position_m.find(index)->second; if(reverse) pos = (pos == 0 ? orderd_m.size() - 1 : pos - 1); else pos = (pos == ordered.size() - 1 ? 0 : pos + 1); return all_unordered_m[ordered_m[pos]]; } }; Given that: I do need all of the data-structures for other purposes; I cannot change them because I need to access the strings: by their id in the all_unordered_m; by their index inside the various ordered_m; I need to know the position of a string (identified by it's position in the first vector) inside ordered_m vector; I cannot change the string_after interface without changing most of the program. How can I speed up the string_after method that is called billions of times and is eating up about 10% of the execution time?

  Read the article

• 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?

  Read the article

< Previous Page | 140 141 142 143 144 145 146 147 148 149 150 151  | Next Page >