Search Results

Search found 585 results on 24 pages for 'numerical equations'.

Page 17/24 | < Previous Page | 13 14 15 16 17 18 19 20 21 22 23 24  | Next Page >

• side effect gotchas in python/numpy? horror stories and narrow escapes wanted

  - by shabbychef

  I am considering moving from Matlab to Python/numpy for data analysis and numerical simulations. I have used Matlab (and SML-NJ) for years, and am very comfortable in the functional environment without side effects (barring I/O), but am a little reluctant about the side effects in Python. Can people share their favorite gotchas regarding side effects, and if possible, how they got around them? As an example, I was a bit surprised when I tried the following code in Python: lofls = [[]] * 4 #an accident waiting to happen! lofls[0].append(7) #not what I was expecting... print lofls #gives [[7], [7], [7], [7]] #instead, I should have done this (I think) lofls = [[] for x in range(4)] lofls[0].append(7) #only appends to the first list print lofls #gives [[7], [], [], []] thanks in advance

  Read the article

• Where can I find simple beta cdf implementation.

  - by Gacek

  I need to use beta distribution and inverse beta distribution in my project. There is quite good but complicated implementation in GSL, but I don't want to use such a big library only to get one function. I would like to either, implement it on my own or link some simple library. Do you know any sources that could help me? I'm looking for any books/articles about numerical approximation of beta PDF, libraries where it could be implemented. Any other suggestions would be also appreciated. Any programming language, but C++/C# preffered.

  Read the article

• Equivalent of LaTeX's \label and \ref in HTML.

  - by dreeves

  I have an FAQ in HTML (example) in which the questions refer to each other a lot. That means whenever we insert/delete/rearrange the questions, the numbering changes. LaTeX solves this very elegantly with \label and \ref -- you give items simple tags and LaTeX worries about converting to numbers in the final document. How do people deal with that in HTML? ADDED: Note that this is no problem if you don't have to actually refer to items by number, in which case you can set a tag with <a name="foo"> and then link to it with <a href="#foo">some non-numerical way to refer to foo</a>. But I'm assuming "foo" has some auto-generated number, say from an <ol> list, and I want to use that number to refer to and link to it.

  Read the article

• pgf/tikz: String Symbols as Input Coordinates

  - by red_lynx

  Hi all, I'm new to pgf so i was trying out some examples from the pgfplot manual. One example is especially relevant for my current task but, alas, it would not compile. Here is the code: \documentclass[11pt]{article} \usepackage{tikz} \usepackage{pgfplots} \begin{document} \begin{tikzpicture} \begin{axis}[symbolic x coords={a,b,c,d,e,f,g,h,i}] \addplot+[smooth] coordinates { (a,42) (b,50) (c,80) (f,60) (g,62) (i,90)}; \end{axis} \end{tikzpicture} \end{document} the compiler quits with the following error: ! Package PGF Math Error: Could not parse input 'a' as a floating point number, sorry. The unreadable part was near 'a'.. I have no clue how to correct this behavior. Other plots (smooth, scatter, bar), which contain only numerical data compile fine. Could anybody give me a hint? Cheers K.

  Read the article

• c# Regex on XML string handler

  - by Dan Sewell

  Hi guys. Trying to fiddle around with regex here, my first attempt. Im trying to extract some figures out of content from an XML tag. The content looks like this: www.blahblah.se/maps.aspx?isAlert=true&lat=51.958855252721&lon=-0.517657021473527 I need to extract the lat and long numerical vales out of each link. They will always be the same amount of characters, and the lon may or may not have a "-" sign. I thought about doing something like this below: (The string in question is in the "link" tag): var document = XDocument.Load(e.Result); if (document.Root == null) return; var events = from ev in document.Descendants("item1") select new { Title = (ev.Element("title").Value), Latitude = Regex.xxxxxxx(ev.Element("link").Value, @"lat=(?<Lat>[+-]?\d*\.\d*)", String.Empty), Longitude = Convert.ToDouble(ev.Element("link").Value), }; foreach (var ev in events) { do stuff } Many thanks!

  Read the article

• C++ password masking

  - by blaxc

  hi... i'm writing a code to receive password input. Below is my code... the program run well but the problem is other keys beside than numerical and alphabet characters also being read, for example delete, insert, and etc. can i know how can i avoid it? tq... string pw=""; char c=' '; while(c != 13) //Loop until 'Enter' is pressed { c = _getch(); if(c==13) break; if(c==8) { if(pw.size()!=0) //delete only if there is input { cout<<"\b \b"; pw.erase(pw.size()-1); } } if((c>47&&c<58)||(c>64&&c<91)||(c>96&&c<123)) //ASCii code for integer and alphabet { pw += c; cout << "*"; } }

  Read the article

• Validating an integer or String without try-catch

  - by Phil

  Ok, I'm lost. I am required to figure out how to validate an integer and String, but for some stupid reason, I can't use the Try-Catch method. I know this is the easiest way and so all the solutions on the internet are using it. I'm writing in Java. The deal is this, I need someone to put in an numerical ID and String name. If either one of the two inputs are invalid I must tell them they made a mistake. Can someone help me?

  Read the article

• Capture String from Array, C#

  - by Dan Snyder

  I'm trying to figure out how to get a string from an array starting at some given position. Say we have an array that's arbitrarily long and my string starts at location 1000. If I wanted to get a string from a file I would simply use something like getc or scanf or something. How do I carry out these same functions on an array instead of a file? *oh, keep in mind that the array is of type int and is full of numerical representations of ASCII characters.

  Read the article

• Doctrine enum type by value

  - by MitMaro

  I have a column in a table defined as following in my yaml file: myTable: columns: value: type: enum length: 2 values: ['yes', 'no'] In the code I am trying to insert data into this table but I can't figure out a way to insert the data using the enum text value (ie. 'yes' or 'no'). What I was trying was is something like this: $obj = new myTable(); // the model for this table $obj->value = 'yes'; // if I use the numerical value for this it works I am using Doctrine 1.1.0.

  Read the article

• Mapping words to numbers with respect to definition

  - by thornate

  As part of a larger project, I need to read in text and represent each word as a number. For example, if the program reads in "Every good boy deserves fruit", then I would get a table that converts 'every' to '1742', 'good' to '977513', etc. Now, obviously I can just use a hashing algorithm to get these numbers. However, it would be more useful if words with similar meanings had numerical values close to each other, so that 'good' becomes '6827' and 'great' becomes '6835', etc. As another option, instead of a simple integer representing each number, it would be even better to have a vector made up of multiple numbers, eg (lexical_category, tense, classification, specific_word) where lexical_category is noun/verb/adjective/etc, tense is future/past/present, classification defines a wide set of general topics and specific_word is much the same as described in the previous paragraph. Does any such an algorithm exist? If not, can you give me any tips on how to get started on developing one myself? I code in C++.

  Read the article

• Assigned numbers to movie clip to plug in formula... not working

  - by Matthew MlgPro Harding

  So I am attempting to vertically evenly space these movie clips so I came up with a math formula involving n( the button number) but Its not working. var buttonArray:Array = [ side_banner.btn1, side_banner.btn2, side_banner.btn3, side_banner.btn4]; var buttonCount:uint = buttonArray.length; for (var i:uint=0; i< buttonCount; i++) { buttonArray[i].addEventListener(MouseEvent.CLICK, outputNumber); buttonArray[i].theTrigger = [i + 1]; } function outputNumber(e:MouseEvent):void { trace( e.target.theTrigger); buttonArray[i].y = (((stage.stageHeight - 400)/4)*(e.target.theTrigger)) - ((stage.stageHeight - 400)/4)/2 } But apparently each movie clip doesn't actually have a numerical value just a numeric name... how can I get the "n" btn number to use my formula? Thanks

  Read the article

• Find model records by ID in the order the array of IDs were given

  - by defaye

  I have a query to get the IDs of people in a particular order, say: ids = [1, 3, 5, 9, 6, 2] I then want to fetch those people by Person.find(ids) But they are always fetched in numerical order, I know this by performing: people = Person.find(ids).map(&:id) => [1, 2, 3, 5, 6, 9] How can I run this query so that the order is the same as the order of the ids array? I made this task more difficult as I wanted to only perform the query to fetch people once, from the IDs given. So, performing multiple queries is out of the question. I tried something like: ids.each do |i| person = people.where('id = ?', i) But I don't think this works.

  Read the article

• erroneous Visual C float / double conversion?

  - by RED SOFT ADAIR

  In Visual C++ i wrote the following sample in a C++ program: float f1 = 42.48f; double d1 = 42.48; double d2 = f1; I compiled the program with Visual Studio 2005. In the debugger i see the following values: f1 42.480000 float d1 42.479999999999997 double d2 42.479999542236328 double d1 by my knowledege is OK, but d2 is wrong. The problem occurs as well with /fp=precise as with /fp=strict as with /fp=fast. Whats the problem here? Any hint how to avoid this Problem? This leads to serious numerical problems.

  Read the article

• Is there any way to modify a column before it is ordered in MySQL?

  - by George Edison

  I have a table with a field value which is a varchar(255). The contents of the field can be quite varied: $1.20 $2994 $56 + tax (This one can be ignored or truncated to $56 if necessary) I have a query constructed: SELECT value FROM unnamed_table ORDER BY value However, this of course uses ASCII string comparison to order the results and does not use any numerical type of comparison. Is there a way to truly order by value without changing the field type to DECIMAL or something else? In other words, can the value field be modified ('$' removed, value converted to decimal) on the fly before the results are sorted?

  Read the article

• Getting specific values with regex [JAVA, ANDROID]

  - by David

  I need to knowingly isolate each row of the vcard and get its value. For instance, I want to get "5555" from X-CUSTOMFIELD. So far, my thoughts are: "X-CUSTOMFIELD;\d+" I have been looking at some tutorials and I am a little confused with what function to use? What would my regex above return? Would it give me the whole line or just the numerical part (5555)? I was thinking I i get the whole row, I can use substring to get the digits? BEGIN:VCARD VERSION:2.1 N:Last;First; FN:First Last TEL;HOME;VOICE:111111 TEL;MOBILE;VOICE:222222 X-CUSTOMFIELD;5555 END:VCARD

  Read the article

• Mapping multiple keys to the same value in a Javascript hash

  - by Bears will eat you

  I use a Javascript hash object to store a set of numerical counters, set up like this [this is greatly simplified]: var myHash = { A: 0, B: 0, C: 0 }; Is there a way to make other keys, ones not explicitly in myHash, map to keys that are? For instance, I'd like [again, this is simplified]: myHash['A_prime']++; // or myHash.A_prime++; to be exactly equivalent to myHash['A']++; // or myHash.A++; e.g. incrementing the value found at the key A, not A_prime.

  Read the article

• What is it about Fibonacci numbers?

  - by Ian Bishop

  Fibonacci numbers have become a popular introduction to recursion for Computer Science students and there's a strong argument that they persist within nature. For these reasons, many of us are familiar with them. They also exist within Computer Science elsewhere too; in surprisingly efficient data structures and algorithms based upon the sequence. There are two main examples that come to mind: Fibonacci heaps which have better amortized running time than binomial heaps. Fibonacci search which shares O(log N) running time with binary search on an ordered array. Is there some special property of these numbers that gives them an advantage over other numerical sequences? Is it a density quality? What other possible applications could they have? It seems strange to me as there are many natural number sequences that occur in other recursive problems, but I've never seen a Catalan heap.

  Read the article

• Can i have a negative value as constant expression in Scala?

  - by Klinke

  I have an Java-Annotation that return a double value: @Retention(RetentionPolicy.RUNTIME) @Target(ElementType.FIELD) public @interface DoubleValue { double value(); } When i try to attach the annotation to a field in a scala class and the value is negativ like here: class Test { @DoubleValue(-0.05) var a = _ } i get an compiler error with the message: "annotation argument needs to be a constant; found: 0.05.unary_-". I understood that i need a numerical literal and i looked into the Scala Language Specification and it seems, that the - sign is only used for the exponent but not for the mantissa. Does someone has an idea how i can have a negative value as runtime information using annotations? Thanks, Klinke

  Read the article

• MySQL load data null values

  - by SP1

  Hello, I have a file that can contain from 3 to 4 columns of numerical values which are separated by comma. Empty fields are defined with the exception when they are at the end of the row: 1,2,3,4,5 1,2,3,,5 1,2,3 The following table was created in MySQL: +-------+--------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+--------+------+-----+---------+-------+ | one | int(1) | YES | | NULL | | | two | int(1) | YES | | NULL | | | three | int(1) | YES | | NULL | | | four | int(1) | YES | | NULL | | | five | int(1) | YES | | NULL | | +-------+--------+------+-----+---------+-------+ I am trying to load the data using MySQL LOAD command: load data infile '/tmp/testdata.txt' into table moo fields terminated by "," lines terminated by "\n"; The resulting table: +------+------+-------+------+------+ | one | two | three | four | five | +------+------+-------+------+------+ | 1 | 2 | 3 | 4 | 5 | | 1 | 2 | 3 | 0 | 0 | | 1 | 2 | 3 | NULL | NULL | +------+------+-------+------+------+ The problem lies with the fact that when a field is empty in the raw data and is not defined, MySQL for some reason does not use the columns default value (which is NULL) and uses zero. NULL is used correctly when the field is missing alltogether. Unfortunately, I have to be able to distinguish between NULL and 0 at this stage so any help would be appreciated. Thanks S.

  Read the article

• Should I bundle C libraries with my Python application?

  - by oceanhug

  If I have a Python package that depends on some C libraries (like say the Gnu Scientific Library (GSL) for numerical computations), is it a good idea to bundle the library with my code? I'd like to make my package as easy to install as possible for users and I don't want them to have to download C libraries by hand and supply include-paths. Also I could always ensure that the version of the library that I ship is compatible with my code. However, is it possible that there are clashes if the user has the library installed already, or ar there any other reasons why I shouldn't do this? I know that I can make it easier for users by just providing a binary distribution, but I'd like to avoid having to maintain binary distributions for all possible OSs. So, I'd like to stick to a source distribution, but for the user (who proudly owns a C compiler) installation should be as easy as python setup.py install.

  Read the article

• Sorting a list of variable length integers delimited by decimal points...

  - by brewerdc

  Hey guys, I'm in need of some help. I have a list of delimited integer values that I need to sort. An example: Typical (alpha?) sort: 1.1.32.22 11.2.4 2.1.3.4 2.11.23.1.2 2.3.7 3.12.3.5 Correct (numerical) sort: 1.1.32.22 2.1.3.4 2.3.7 2.11.23.1.2 3.12.3.5 11.2.4 I'm having trouble figuring out how to setup the algorithm to do such a sort with n number of decimal delimiters and m number of integer fields. Any ideas? This has to have been done before. Let me know if you need more information. Thanks a bunch! -Daniel

  Read the article

• Javascript array length incorrect on array of objects

  - by Serenti

  Could someone explain this (strange) behavior? Why is the length in the first example 3 and not 2, and most importantly, why is the length in the second example 0? As long as the keys are numerical, length works. When they are not, length is 0. How can I get the correct length from the second example? Thank you. a = []; a["1"] = {"string1":"string","string2":"string"}; a["2"] = {"string1":"string","string2":"string"}; alert(a.length); // returns 3 b = []; b["key1"] = {"string1":"string","string2":"string"}; b["key2"] = {"string1":"string","string2":"string"}; alert(b.length); // returns 0

  Read the article

• Remove adjacent identical elements in a Ruby Array?

  - by Mike Woodhouse

  Ruby 1.8.6 I have an array containing numerical values. I want to reduce it such that sequences of the same value are reduced to a single instance of that value. So I want a = [1, 1, 1, 2, 2, 3, 3, 3, 3, 2, 2, 2, 3, 3, 3] to reduce to [1, 2, 3, 2, 3] As you can see, Array#uniq won't work in this case. I have the following, which works: (a.size - 1).downto(1) { |i| a[i] = nil if a[i - 1] == a[i] } Can anyone come up with something less ugly?

  Read the article

• MATLAB: Automatic detection of relations between workspace variables through functions

  - by Peterstone

  Hi all, I´m trying to write a function what detect this relation between the variables I have got in the workspace: v1 - fft(v2) = 0 Where v1, v2 are variables of my workspace. Sometimes I need to know which variables have a certain numerical relation. If I have thirty, I don´t want to be looking for this relation in "manual way", just itroducing a sentence for each pair of different variables. I would like a function in which I introuce (or I modify this function every time I need it) the sentence (for instance what I wrote before) and the function show me the pair of variables a I am looking for. Does anyone know how to do it? Thank you so much!

  Read the article

• Ignore route with a specific parameter

  - by Vivien

  Hello, I have an @url.Action in which I pass a parameter to the action. When the parameter is null, I would like to just do nothing and stay on the same page. What I have done is the following: routes.MapRoute( null, "Test/View/{Id}", new { controller = "Test", action = "View" }, new { Id = @"\d+" } //id must be numerical ); routes.IgnoreRoute("Test/View/{*pathInfo}"); The action is not executed but my problem is that I get this: Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable. Please review the following URL and make sure that it is spelled correctly. Requested URL: /Test/View Which I obvisouly do not want to see. Thanks for your help.

  Read the article

< Previous Page | 13 14 15 16 17 18 19 20 21 22 23 24  | Next Page >