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  • What's going on here? Repeating rows in random list of lists.

    - by Jesse Aldridge
    I expected to get a grid of unique random numbers. Instead each row is the same sequence of numbers. What's going on here? from pprint import pprint from random import random nrows, ncols = 5, 5 grid = [[0] * ncols] * nrows for r in range(nrows): for c in range(ncols): grid[r][c] = int(random() * 100) pprint(grid) Example output: [[64, 82, 90, 69, 36], [64, 82, 90, 69, 36], [64, 82, 90, 69, 36], [64, 82, 90, 69, 36], [64, 82, 90, 69, 36]]

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  • Challenge: Neater way of currying or partially applying C#4's string.Join

    - by Damian Powell
    Background I recently read that .NET 4's System.String class has a new overload of the Join method. This new overload takes a separator, and an IEnumerable<T> which allows arbitrary collections to be joined into a single string without the need to convert to an intermediate string array. Cool! That means I can now do this: var evenNums = Enumerable.Range(1, 100) .Where(i => i%2 == 0); var list = string.Join(",",evenNums); ...instead of this: var evenNums = Enumerable.Range(1, 100) .Where(i => i%2 == 0) .Select(i => i.ToString()) .ToArray(); var list = string.Join(",", evenNums); ...thus saving on a conversion of every item to a string, and then the allocation of an array. The Problem However, being a fan of the functional style of programming in general, and method chaining in C# in particular, I would prefer to be able to write something like this: var list = Enumerable.Range(1, 100) .Where(i => i%2 == 0) .string.Join(","); This is not legal C# though. The closest I've managed to get is this: var list = Enumerable.Range(1, 100) .Where(i => i%2 == 0) .ApplyTo( Functional.Curry<string, IEnumerable<object>, string> (string.Join)(",") ); ...using the following extension methods: public static class Functional { public static TRslt ApplyTo<TArg, TRslt>(this TArg arg, Func<TArg, TRslt> func) { return func(arg); } public static Func<T1, Func<T2, TResult>> Curry<T1, T2, TResult>(this Func<T1, T2, TResult> func) { Func<Func<T1, T2, TResult>, Func<T1, Func<T2, TResult>>> curried = f => x => y => f(x, y); return curried(func); } } This is quite verbose, requires explicit definition of the parameters and return type of the string.Join overload I want to use, and relies upon C#4's variance features because we are defining one of the arguments as IEnumerable rather than IEnumerable. The Challenge Can you find a neater way of achieving this using the method-chaining style of programming?

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  • Opencart Dashboard show last months statistics

    - by John Magnolia
    How could I added the option to show the statistics for last month. PHP public function chart() { $this->load->language('common/home'); $data = array(); $data['order'] = array(); $data['customer'] = array(); $data['xaxis'] = array(); $data['order']['label'] = $this->language->get('text_order'); $data['customer']['label'] = $this->language->get('text_customer'); if (isset($this->request->get['range'])) { $range = $this->request->get['range']; } else { $range = 'month'; } switch ($range) { case 'day': for ($i = 0; $i < 24; $i++) { $query = $this->db->query("SELECT COUNT(*) AS total FROM `" . DB_PREFIX . "order` WHERE order_status_id > '0' AND (DATE(date_added) = DATE(NOW()) AND HOUR(date_added) = '" . (int)$i . "') GROUP BY HOUR(date_added) ORDER BY date_added ASC"); if ($query->num_rows) { $data['order']['data'][] = array($i, (int)$query->row['total']); } else { $data['order']['data'][] = array($i, 0); } $query = $this->db->query("SELECT COUNT(*) AS total FROM " . DB_PREFIX . "customer WHERE DATE(date_added) = DATE(NOW()) AND HOUR(date_added) = '" . (int)$i . "' GROUP BY HOUR(date_added) ORDER BY date_added ASC"); if ($query->num_rows) { $data['customer']['data'][] = array($i, (int)$query->row['total']); } else { $data['customer']['data'][] = array($i, 0); } $data['xaxis'][] = array($i, date('H', mktime($i, 0, 0, date('n'), date('j'), date('Y')))); } break; case 'week': $date_start = strtotime('-' . date('w') . ' days'); for ($i = 0; $i < 7; $i++) { $date = date('Y-m-d', $date_start + ($i * 86400)); $query = $this->db->query("SELECT COUNT(*) AS total FROM `" . DB_PREFIX . "order` WHERE order_status_id > '0' AND DATE(date_added) = '" . $this->db->escape($date) . "' GROUP BY DATE(date_added)"); if ($query->num_rows) { $data['order']['data'][] = array($i, (int)$query->row['total']); } else { $data['order']['data'][] = array($i, 0); } $query = $this->db->query("SELECT COUNT(*) AS total FROM `" . DB_PREFIX . "customer` WHERE DATE(date_added) = '" . $this->db->escape($date) . "' GROUP BY DATE(date_added)"); if ($query->num_rows) { $data['customer']['data'][] = array($i, (int)$query->row['total']); } else { $data['customer']['data'][] = array($i, 0); } $data['xaxis'][] = array($i, date('D', strtotime($date))); } break; default: case 'month': for ($i = 1; $i <= date('t'); $i++) { $date = date('Y') . '-' . date('m') . '-' . $i; $query = $this->db->query("SELECT COUNT(*) AS total FROM `" . DB_PREFIX . "order` WHERE order_status_id > '0' AND (DATE(date_added) = '" . $this->db->escape($date) . "') GROUP BY DAY(date_added)"); if ($query->num_rows) { $data['order']['data'][] = array($i, (int)$query->row['total']); } else { $data['order']['data'][] = array($i, 0); } $query = $this->db->query("SELECT COUNT(*) AS total FROM " . DB_PREFIX . "customer WHERE DATE(date_added) = '" . $this->db->escape($date) . "' GROUP BY DAY(date_added)"); if ($query->num_rows) { $data['customer']['data'][] = array($i, (int)$query->row['total']); } else { $data['customer']['data'][] = array($i, 0); } $data['xaxis'][] = array($i, date('j', strtotime($date))); } break; case 'year': for ($i = 1; $i <= 12; $i++) { $query = $this->db->query("SELECT COUNT(*) AS total FROM `" . DB_PREFIX . "order` WHERE order_status_id > '0' AND YEAR(date_added) = '" . date('Y') . "' AND MONTH(date_added) = '" . $i . "' GROUP BY MONTH(date_added)"); if ($query->num_rows) { $data['order']['data'][] = array($i, (int)$query->row['total']); } else { $data['order']['data'][] = array($i, 0); } $query = $this->db->query("SELECT COUNT(*) AS total FROM " . DB_PREFIX . "customer WHERE YEAR(date_added) = '" . date('Y') . "' AND MONTH(date_added) = '" . $i . "' GROUP BY MONTH(date_added)"); if ($query->num_rows) { $data['customer']['data'][] = array($i, (int)$query->row['total']); } else { $data['customer']['data'][] = array($i, 0); } $data['xaxis'][] = array($i, date('M', mktime(0, 0, 0, $i, 1, date('Y')))); } break; } $this->response->setOutput(json_encode($data)); } HTML <select name="range"> <option value="day">Today</option> <option value="week">This Week</option> <option value="month">This Month</option> <option value="year">This Year</option> </select>

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  • Suggestion for a Data Structure!

    - by Jay
    I have the following requirements for a data structure: Direct access to an element with the help of a key (Key will be an integer, range is also same as integer range) Avoid memory allocation in chunks (Allocate contigous memory for the data structure including the data) Should be able to grow the data structure size dynamically Which data structure would you suggest? Any pointers in the direction will also be of help.

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  • ASP.NET MVC - PartialView html not changing via jQuery html() call

    - by Bryan Roth
    When I change the selection in a DropDownList, a PartialView gets updated via a GET request. When updating the PartialView via the jQuery html() function, the html returned is correct but when it displayed in the browser it is not correct. For example, certain checkboxes within the PartialView should become enabled but they remain disabled even though the html returned says they should be. When I do a view source in the browser the html never gets updated. I'm a little perplexed. Thoughts? Search.aspx <%@ Page Title="" Language="VB" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Search </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <script type="text/javascript"> $(document).ready(function () { $("#Sections").change(function () { var section = $("#Sections").val(); var township = $("#Townships").val(); var range = $("#Ranges").val(); $.get("Search/Search?section=" + section + "&township=" + township + "&range=" + range, function (response) { $("#cornerDiv").html(response) }); }); }); </script> <h2>Search</h2> <%--The line below is a workaround for a VB / ASPX designer bug--%> <%=""%> <% Using Ajax.BeginForm("Search", New AjaxOptions With {.UpdateTargetId = "searchResults", .LoadingElementId = "loader"})%> Township <%= Html.DropDownList("Townships")%> Range <%= Html.DropDownList("Ranges")%> Section <%= Html.DropDownList("Sections")%> <div id="cornerDiv"> <% Html.RenderPartial("Corners")%> </div> <input type="submit" value="Search" /> <span id="loader">Searching...</span> <% End Using%> <div id="searchResults"></div> </asp:Content>

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  • Location detecting tecniques for IP addresses

    - by ilhan
    What are the location detecting tecniques for IP adresses? I know to look at the $_SERVER['HTTP_ACCEPT_LANGUAGE'] (not accurate but mostly useful to detect location, for example if an IP range's users set French to their browser then it means that this range) belongs to France and gethostbyaddr($_SERVER['REMOTE_ADDR']) (to look country code top-level domain) then may be to whois gethostbyaddr($_SERVER['REMOTE_ADDR']) sometimes: $HTTP_USER_AGENT (Firefox's user agent string has language code, not accurate but mostly can be used to detect the location) But what about cities?

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  • Parametrizing max value of a jQuery ui slider

    - by Gandalf StormCrow
    I'm trying to create this slider http://jqueryui.com/demos/slider/#rangemax Is it possible to parametrize the max value? For ex: $("#slider-range-max").slider({ range: "max", min: 1, max: maxValue, value: 2, slide: function(event, ui) { $("#amount").val(ui.value); } }); Is it possible to pass maxValue value, when I click on something? After its been initialized? Not on document ready function, but even after that?

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  • Difference between generator expression and generator function

    - by Neil G
    Is there any difference — performance or otherwise — between generator expressions and generator functions? In [1]: def f(): ...: yield from range(4) ...: In [2]: def g(): ...: return (i for i in range(4)) ...: In [3]: f() Out[3]: <generator object f at 0x109902550> In [4]: list(f()) Out[4]: [0, 1, 2, 3] In [5]: list(g()) Out[5]: [0, 1, 2, 3] In [6]: g() Out[6]: <generator object <genexpr> at 0x1099056e0>

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  • Find Line Above or Below in Javascript

    - by Dark Falcon
    I am working on an in-place HTML editor, concentrating on Firefox only right now. I have an element inserted where the cursor should be and also have left and right arrows working, but I can't seem to find a way to find: Start and end of a line for the home and end keys The next line up or down for the up/down arrows. I see document.elementFromPoint, but this doesn't get me a Range object. The Range object itself seems rather useless when it comes to using pixel positions.

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  • Mapping a BigInteger to a circle

    - by Martin
    I have a C# system using 160 bit numbers, stored in a BigInteger. I want to display these things on a circle, which means mapping the 0-2^160 range into the 0-2Pi range. How would I do this? The approach that jumps instantly to mind is angle = (number / pow(2, 160)) * TwoPi; However, that has complexities because the division will truncate the result into an integer.

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  • some unclear php "symbolics"

    - by serhio
    I am a php beginner and seed on the forum such a php expression: $regex = <<<'END' / ( [\x00-\x7F] # single-byte sequences 0xxxxxxx | [\xC0-\xDF][\x80-\xBF] # double-byte sequences 110xxxxx 10xxxxxx | [\xE0-\xEF][\x80-\xBF]{2} # triple-byte sequences 1110xxxx 10xxxxxx * 2 | [\xF0-\xF7][\x80-\xBF]{3} # quadruple-byte sequence 11110xxx 10xxxxxx * 3 ) | ( [\x80-\xBF] ) # invalid byte in range 10000000 - 10111111 | ( [\xC0-\xFF] ) # invalid byte in range 11000000 - 11111111 /x END; is this code correct? what should mean some strange (4 me) constructions like <<< 'END' / /x and END; thanks

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  • State machines in C#

    - by Sir Psycho
    Hi, I'm trying to work out what's going on with this code. I have two threads iterating over the range and I'm trying to understand what is happening when the second thread calls GetEnumerator(). This line in particular (T current = start;), seems to spawn a new 'instance' in this method by the second thread. Seeing that there is only one instance of the DateRange class, I'm trying to understand why this works. Thanks in advance. class Program { static void Main(string[] args) { var daterange = new DateRange(DateTime.Now, DateTime.Now.AddDays(10), new TimeSpan(24, 0, 0)); var ts1 = new ThreadStart(delegate { foreach (var date in daterange) { Console.WriteLine("Thread " + Thread.CurrentThread.ManagedThreadId + " " + date); } }); var ts2 = new ThreadStart(delegate { foreach (var date in daterange) { Console.WriteLine("Thread " + Thread.CurrentThread.ManagedThreadId + " " + date); } }); Thread t1 = new Thread(ts1); Thread t2 = new Thread(ts2); t1.Start(); Thread.Sleep(4000); t2.Start(); Console.Read(); } } public class DateRange : Range<DateTime> { public DateTime Start { get; private set; } public DateTime End { get; private set; } public TimeSpan SkipValue { get; private set; } public DateRange(DateTime start, DateTime end, TimeSpan skip) : base(start, end) { SkipValue = skip; } public override DateTime GetNextElement(DateTime current) { return current.Add(SkipValue); } } public abstract class Range<T> : IEnumerable<T> where T : IComparable<T> { readonly T start; readonly T end; public Range(T start, T end) { if (start.CompareTo(end) > 0) throw new ArgumentException("Start value greater than end value"); this.start = start; this.end = end; } public abstract T GetNextElement(T currentElement); public IEnumerator<T> GetEnumerator() { T current = start; do { Thread.Sleep(1000); yield return current; current = GetNextElement(current); } while (current.CompareTo(end) < 1); } System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return GetEnumerator(); } }

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  • Interview question: f(f(n)) == -n

    - by Hrvoje Prgeša
    A question I got on my last interview: Design a function f, such that: f(f(n)) == -n Where n is a 32 bit signed integer; you can't use complex numbers arithmetic. If you can't design such a function for the whole range of numbers, design it for the largest range possible. Any ideas?

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  • Location detecting tecniques for IP adresses

    - by ilhan
    What are the location detecting tecniques for IP adresses? I know to look at the $_SERVER['HTTP_ACCEPT_LANGUAGE'] (not accurate but mostly useful to detect location, for example if an IP range's users set French to their browser then it means that this range belongs to France gethostbyaddr($_SERVER['REMOTE_ADDR']) then may be to whois gethostbyaddr($_SERVER['REMOTE_ADDR']) sometimes $HTTP_USER_AGENT (Firefox's user agent string has language code, not accurate but mostly can be used to detect the location) But what about cities?

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  • c++ quick sort running time

    - by chnet
    I have a question about quick sort algorithm. I implement quick sort algorithm and play it. The elements in initial unsorted array are random numbers chosen from certain range. I find the range of random number effects the running time. For example, the running time for 1, 000, 000 random number chosen from the range (1 - 2000) takes 40 seconds. While it takes 9 seconds if the 1,000,000 number chosen from the range (1 - 10,000). But I do not know how to explain it. In class, we talk about the pivot value can effect the depth of recursion tree. For my implementation, the last value of the array is chosen as pivot value. I do not use randomized scheme to select pivot value. int partition( vector<int> &vec, int p, int r) { int x = vec[r]; int i = (p-1); int j = p; while(1) { if (vec[j] <= x){ i = (i+1); int temp = vec[j]; vec[j] = vec[i]; vec[i] = temp; } j=j+1; if (j==r) break; } int temp = vec[i+1]; vec[i+1] = vec[r]; vec[r] = temp; return i+1; } void quicksort ( vector<int> &vec, int p, int r) { if (p<r){ int q = partition(vec, p, r); quicksort(vec, p, q-1); quicksort(vec, q+1, r); } } void random_generator(int num, int * array) { srand((unsigned)time(0)); int random_integer; for(int index=0; index< num; index++){ random_integer = (rand()%10000)+1; *(array+index) = random_integer; } } int main() { int array_size = 1000000; int input_array[array_size]; random_generator(array_size, input_array); vector<int> vec(input_array, input_array+array_size); clock_t t1, t2; t1 = clock(); quicksort(vec, 0, (array_size - 1)); // call quick sort int length = vec.size(); t2 = clock(); float diff = ((float)t2 - (float)t1); cout << diff << endl; cout << diff/CLOCKS_PER_SEC <<endl; }

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  • Distinct rand() sequences yielding the same results in an expression

    - by suszterpatt
    Ok, this is a really weird one. I have an MPI program, where each process has to generate random numbers in a fixed range (the range is read from file). What happens is that even though I seed each process with a different value, and the numbers generated by rand() are different in each process, the expression to generate the random numbers still yields the same sequence between them. Here's all relevant code: // 'rank' will be unique for each process int rank; MPI_Comm_rank(MPI_COMM_WORLD, &rank); // seed the RNG with a different value for each process srand(time(NULL) + rank); // print some random numbers to see if we get a unique sequence in each process // 'log' is a uniquely named file, each process has its own log << rand() << " " << rand() << " " << rand() << std::endl; // do boring deterministic stuff while (true) { // waitTimeMin and waitTimeMax are integers, Max is always greater than Min waitSecs = waitTimeMin + rand() % (waitTimeMax - waitTimeMin); log << "waiting " << waitSecs << " seconds" << std::endl; sleep(waitSecs); // do more boring deterministic stuff } Here's the output of each process, with 3 processes generating numbers in the range [1,9]. process 1: 15190 28284 3149 waiting 6 seconds waiting 8 seconds waiting 9 seconds waiting 4 seconds process 2: 286 6264 3153 waiting 6 seconds waiting 8 seconds waiting 9 seconds waiting 4 seconds process 3: 18151 17013 3156 waiting 6 seconds waiting 8 seconds waiting 9 seconds waiting 4 seconds So while rand() clearly generates different numbers, the expression to calculate waitSecs still evaluates to the same sequence on all processes. What's even weirder: if I run the program with the same parameteres again, only the first 3 random numbers will change, the rest of the "random" sequence will be exactly the same in each run! Changing the range of numbers will obviously produce a different result from this one, but the same parameters always yield the same sequence, between processes and between executions: except for the first 3 numbers. Just what the hell is going on here?

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  • Trouble with encoding and urllib

    - by Ockonal
    Hello, I'm loading web-page using urllib. Ther eis russian symbols, but page encoding is 'utf-8' 1 pageData = unicode(requestHandler.read()).decode('utf-8') UnicodeDecodeError: 'ascii' codec can't decode byte 0xd0 in position 262: ordinal not in range(128) 2 pageData = requestHandler.read() soupHandler = BeautifulSoup(pageData) print soupHandler.findAll(...) UnicodeEncodeError: 'ascii' codec can't encode characters in position 340-345: ordinal not in range(128)

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  • How to make a report with count of type of cases in each month in Acess 2010

    - by amir shadaab
    I have a database is access with each record having a date and yes/no type columns for each record which shows which category the record comes under. I want to create a report which shows the types of cases in each month by taking a date range as a parameter through prompts. I have done the prompt part but I'm not sure how the query should be to show values for each month in that date range. Can someone please help me with this?

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  • Parameterizing max value of a jQuery ui slider

    - by Gandalf StormCrow
    I'm trying to create this slider http://jqueryui.com/demos/slider/#rangemax Is it possible to parametrize the max value? For ex: $("#slider-range-max").slider({ range: "max", min: 1, max: maxValue, value: 2, slide: function(event, ui) { $("#amount").val(ui.value); } }); Is it possible to pass maxValue value, when I click on something? After its been initialized? Not on document ready function, but even after that?

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  • populate combox on windows mobile 5.0

    - by user315502
    Hi, I try populate combobox in windows mobile 5.0 pocket pc but i have this error: Value does not fall within the expected range. the datatable return from dataset on the webservice: the method is: Value does not fall within the expected range public void loadComboBox(ref ComboBox ComboBoxGen, string DisplayText, string Value,DataTable dt) { ComboBoxGen.DataSource = dt; ComboBoxGen.DisplayMember = DisplayText; ComboBoxGen.ValueMember = Value; }

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  • automatically execute an Excel macro on a cell change

    - by namin
    How can I automatically execute an Excel macro each time a value in a particular cell changes? Right now, my working code is: Private Sub Worksheet_Change(ByVal Target As Range) If Not Intersect(Target, Range("H5")) Is Nothing Then Macro End Sub where "H5" is the particular cell being monitored and Macro is the name of the macro. Is there a better way?

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  • Excel: Make conditional formatting static

    - by Martin
    Is there any way to convert conditional formatting to static formatting in Excel? I'm trying to export a range of a Excel Sheet to a new Workbook, with identical appearance but no formulas, links, etc. The problem here is that I have conditional formatting that relies on calculations outside exported range. I've tried saving the workbook to .html, oddly enough the formatting shows in IE but not when reopening it in Excel.

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  • How to check for palindrome using Python logic

    - by DrOnline
    My background is only a 6 month college class in basic C/C++, and I'm trying to convert to Python. I may be talking nonsense, but it seems to me C, at least at my level, is very for-loop intensive. I solve most problems with these loops. And it seems to me the biggest mistake people do when going from C to Python is trying to implement C logic using Python, which makes things run slowly, and it's just not making the most of the language. I see on this website: http://hyperpolyglot.org/scripting (serach for "c-style for", that Python doesn't have C-style for loops. Might be outdated, but I interpret it to mean Python has its own methods for this. I've tried looking around, I can't find much up to date (Python 3) advice for this. How can I solve a palindrome challenge in Python, without using the for loop? I've done this in C in class, but I want to do it in Python, on a personal basis. The problem is from the Euler Project, great site btw. def isPalindrome(n): lst = [int(n) for n in str(n)] l=len(lst) if l==0 || l==1: return True elif len(lst)%2==0: for k in range (l) ##### else: while (k<=((l-1)/2)): if (list[]): ##### for i in range (999, 100, -1): for j in range (999,100, -1): if isPalindrome(i*j): print(i*j) break I'm missing a lot of code here. The five hashes are just reminders for myself. Concrete questions: 1) In C, I would make a for loop comparing index 0 to index max, and then index 0+1 with max-1, until something something. How to best do this in Python? 2) My for loop (in in range (999, 100, -1), is this a bad way to do it in Python? 3) Does anybody have any good advice, or good websites or resources for people in my position? I'm not a programmer, I don't aspire to be one, I just want to learn enough so that when I write my bachelor's degree thesis (electrical engineering), I don't have to simultaneously LEARN an applicable programming language while trying to obtain good results in the project. "How to go from basic C to great application of Python", that sort of thing. 4) Any specific bits of code to make a great solution to this problem would also be appreciated, I need to learn good algorithms.. I am envisioning 3 situations. If the value is zero or single digit, if it is of odd length, and if it is of even length. I was planning to write for loops... PS: The problem is: Find the highest value product of two 3 digit integers that is also a palindrome.

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  • Does clustered index on foreign key column increase join performance vs non-clustered ?

    - by alpav
    In many places it's recommended that clustered indexes are better utilized when used to select range of rows using BETWEEN statement. When I select joining by foreign key field in such a way that this clustered index is used, I guess, that clusterization should help too because range of rows is being selected even though they all have same clustered key value and BETWEEN is not used. Considering that I care only about that one select with join and nothing else, am I wrong with my guess ?

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  • approximating log10[x^k0 + k1]

    - by Yale Zhang
    Greetings. I'm trying to approximate the function Log10[x^k0 + k1], where .21 < k0 < 21, 0 < k1 < ~2000, and x is integer < 2^14. k0 & k1 are constant. For practical purposes, you can assume k0 = 2.12, k1 = 2660. The desired accuracy is 5*10^-4 relative error. This function is virtually identical to Log[x], except near 0, where it differs a lot. I already have came up with a SIMD implementation that is ~1.15x faster than a simple lookup table, but would like to improve it if possible, which I think is very hard due to lack of efficient instructions. My SIMD implementation uses 16bit fixed point arithmetic to evaluate a 3rd degree polynomial (I use least squares fit). The polynomial uses different coefficients for different input ranges. There are 8 ranges, and range i spans (64)2^i to (64)2^(i + 1). The rational behind this is the derivatives of Log[x] drop rapidly with x, meaning a polynomial will fit it more accurately since polynomials are an exact fit for functions that have a derivative of 0 beyond a certain order. SIMD table lookups are done very efficiently with a single _mm_shuffle_epi8(). I use SSE's float to int conversion to get the exponent and significand used for the fixed point approximation. I also software pipelined the loop to get ~1.25x speedup, so further code optimizations are probably unlikely. What I'm asking is if there's a more efficient approximation at a higher level? For example: Can this function be decomposed into functions with a limited domain like log2((2^x) * significand) = x + log2(significand) hence eliminating the need to deal with different ranges (table lookups). The main problem I think is adding the k1 term kills all those nice log properties that we know and love, making it not possible. Or is it? Iterative method? don't think so because the Newton method for log[x] is already a complicated expression Exploiting locality of neighboring pixels? - if the range of the 8 inputs fall in the same approximation range, then I can look up a single coefficient, instead of looking up separate coefficients for each element. Thus, I can use this as a fast common case, and use a slower, general code path when it isn't. But for my data, the range needs to be ~2000 before this property hold 70% of the time, which doesn't seem to make this method competitive. Please, give me some opinion, especially if you're an applied mathematician, even if you say it can't be done. Thanks.

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