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• Help with Neuroph neural network

  - by user359708

  For my graduate research I am creating a neural network that trains to recognize images. I am going much more complex than just taking a grid of RGB values, downsampling, and and sending them to the input of the network, like many examples do. I actually use over 100 independently trained neural networks that detect features, such as lines, shading patterns, etc. Much more like the human eye, and it works really well so far! The problem is I have quite a bit of training data. I show it over 100 examples of what a car looks like. Then 100 examples of what a person looks like. Then over 100 of what a dog looks like, etc. This is quite a bit of training data! Currently I am running at about one week to train the network. This is kind of killing my progress, as I need to adjust and retrain. I am using Neuroph, as the low-level neural network API. I am running a dual-quadcore machine(16 cores with hyperthreading), so this should be fast. My processor percent is at only 5%. Are there any tricks on Neuroph performance? Or Java peroformance in general? Suggestions? I am a cognitive psych doctoral student, and I am decent as a programmer, but do not know a great deal about performance programming.

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• Linux RFID reader HID Device not matching driver

  - by blietaer

  Hello, I got a RFID reader (GigaTek PCR330A-00) that is meant to be recognized under linux/windows as a (Human Interface Device) keyboard/USB. I hate to say this but it is working as a charm under Win7 but not "really" under Linux. Under Debian-like distros (x/k/Ubuntu, Debian,..), or Gentoo, or... I just can't have the device working at all: the device scan well (it has its USB 5V, so it is happy/beeping/blinking) something happened in the dmesg, but no immediate screen display of the RFID Tag code as expected (and seen under win7) Support is claiming it is ok under RHEL or SLED "enterprises" distros... and I must admit I saw it working under a RHEL4... I tried stealing the driver but did not succeed having my reader working... My question is thus double: 1./ How can I hack the kernel to add support to my device (simply register PID/VID?) ? 2./ What is different at all in a "enterprise" proprietary distro? how can I re-use it? Thank you for any hint/help. Cheers,

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• Integrating Magento with SAP ECC 6.0 Backend

  - by ikarous

  I'm a freshly graduated (read: inexperienced) developer who's been tasked with determining the feasibility of integrating Magento with an SAP-based backend. No developer at our company has any experience working with either SAP or Magento, so I was hoping that the Stack Overflow community may be able to point me in the right direction with my research. We're a small company (four full-time developers) and the timeline on this project would be tight, so I'm trying to gather as much information as possible. The client has a tiered pricing structure, tax calculation logic, promotional deals, and automatic freight determination all implemented in an SAP ECC 6.0 system. They would like to migrate all their online stores over to Magento while continuing to utilize all existing functionality in SAP. The idea is to accomplish this by overriding certain modules in Magento to place remote calls to SAP BAPIs. I've investigated SAPRFC, which looks promising but relatively stale in terms of update frequency. Do any developers have experience using SAPRFC with SAP ECC 6.0 (with or without Magento integration)? If so, what were your experiences, and what were the biggest risk factors involved? Any comments, suggestions, or links to resources would be greatly appreciated.

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• What's the deal with Java's public fields?

  - by Annan

  I've been reading two articles (1)(2) on javaworld.com about how all class fields should be private and getter/setter methods are just as bad. An object should act on the data it has rather than allowing access to it. I'm currently working on a University assignment for Connect Four. In designing the program the Agents playing the Game need access to the Board's state (so they can decide what to move). They also need to pass this move to the Game so it can validate it as a legal move. And during deciding what to move pieces are grouped into Threats with a start and end Points. Board, Threat and Point objects don't really do anything. They are just there to store related data that can be accessed in a human readable way. At the start of design I was representing Points on the board as two element int arrays, however that got annoying when creating points or referencing components of them. So, the class: public class Point { public int x; public int y; public Point(int x, int y){ this.x = x; this.y = y; } } Perfect in every way I can think of. Except it breaks every rule I've learned. Have I sinned?

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• Obj-C: ++variable is increasing by two instead of one

  - by Eli Garfinkel

  I am writing a program that asks users yes/no questions to help them decide how to vote in an election. I have a variable representing the question number called questionnumber. Each time I go through the switch-break loop, I add 1 to the questionnumber variable so that the next question will be displayed. This works fine for the first two questions. But then it skips the third question and moves on to the fourth. When I have more questions in the list, it skips every other question. Somewhere, for some reasons, the questionnumber variable is increasing when I don't want it to. Please look at the code below and tell me what I'm doing wrong. Thank you! Eli import "MainView.h" import @implementation MainView @synthesize Question; @synthesize mispar; int conservative = 0; int liberal = 0; int questionnumber = 1; (IBAction)agreebutton:(id)sender { ++liberal; } (IBAction)disagreebutton:(id)sender { ++conservative; } (IBAction)nextbutton:(id)sender { ++questionnumber; switch (questionnumber) { case 2: Question.text = @"Congress should pass a law that would ban Americans from earning more than one hundred million dollars in any given year."; break; case 3: Question.text = @"It is not fair to admit people to a university or employ them on the basis of merit alone. Factors such as race, gender, class, and sexual orientation must also be considered."; break; case 4: Question.text = @"There are two Americas - one for the rich and one for the poor."; break; case 5: Question.text = @"Top quality health care should be free for all."; break; default: break; } } @end

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• Is ASP.NET MVC is really MVC? Or how to separate model from controller?

  - by Andrey

  Hi all, This question is a bit rhetorical. At some point i got a feeling that ASP.NET MVC is not that authentic implementation of MVC pattern. Or i didn't understood it. Consider following domain: electric bulb, switch and motion detector. They are connected together and when you enter the room motion detector switches on the bulb. If i want to represent them as MVC: switch is model, because it holds the state and contains logic bulb is view, because it presents the state of model to human motion detector is controller, because it converts user actions to generic model commands Switch has one private field (On/Off) as a State and two methods (PressOn, PressOff). If you call PressOn when it is Off it goes to On, if you call it again state doesn't change. Bulb can be replaced with buzzer, motion detector with timer or button, but the model still represent the same logic. Eventually system will have same behavior. This is how i understand classical MVC decomposition, please correct me if i am wrong. Now let's decompose it in ASP.Net MVC way. Bulb is still a view Controller will be switch + motion detector Model is some object that will just pass state to bulb. So the logic that defines behavior moves to controller. Question 1: Is my understanding of MVC and ASP.NET MVC correct? Question 2: If yes, do you agree that ASP.NET MVC is not 100% accurate implementation? And back to life. The final question is how to separate model from controller in case of ASP.NET MVC. There can be two extremes. Controller does basic stuff and call model to do all the logic. Another is controller does all the logic and model is just something like class with properties that is mapped to DB. Question 3: Where should i draw the line between this extremes? How to balance? Thanks, Andrey

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• Which SCM/VCS cope well with moving text between files?

  - by pfctdayelise

  We are having havoc with our project at work, because our VCS is doing some awful merging when we move information across files. The scenario is thus: You have lots of files that, say, contain information about terms from a dictionary, so you have a file for each letter of the alphabet. Users entering terms blindly follow the dictionary order, so they will put an entry like "kick the bucket" under B if that is where the dictionary happened to list it (or it might have been listed under both B, bucket and K, kick). Later, other users move the terms to their correct files. Lots of work is being done on the dictionary terms all the time. e.g. User A may have taken the B file and elaborated on the "kick the bucket" entry. User B took the B and K files, and moved the "kick the bucket" entry to the K file. Whichever order they end up getting committed in, the VCS will probably lose entries and not "figure out" that an entry has been moved. (These entries are later automatically converted to an SQL database. But they are kept in a "human friendly" form for working on them, with lots of comments, examples etc. So it is not acceptable to say "make your users enter SQL directly".) It is so bad that we have taken to almost manually merging these kinds of files now, because we can't trust our VCS. :( So what is the solution? I would love to hear that there is a VCS that could cope with this. Or a better merge algorithm? Or otherwise, maybe someone can suggest a better workflow or file arrangement to try and avoid this problem?

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• Computing complex math equations in python

  - by dassouki

  Are there any libraries or techniques that simplify computing equations ? Take the following two examples: F = B * { [ a * b * sumOf (A / B ''' for all i ''' ) ] / [ sumOf(c * d * j) ] } where: F = cost from i to j B, a, b, c, d, j are all vectors in the format [ [zone_i, zone_j, cost_of_i_to_j], [..]] This should produce a vector F [ [1,2, F_1_2], ..., [i,j, F_i_j] ] T_ij = [ P_i * A_i * F_i_j] / [ SumOf [ Aj * F_i_j ] // j = 1 to j = n ] where: n is the number of zones T = vector [ [1, 2, A_1_2, P_1_2], ..., [i, j, A_i_j, P_i_j] ] F = vector [1, 2, F_1_2], ..., [i, j, F_i_j] so P_i would be the sum of all P_i_j for all j and Aj would be sum of all P_j for all i I'm not sure what I'm looking for, but perhaps a parser for these equations or methods to deal with multiple multiplications and products between vectors? To calculate some of the factors, for example A_j, this is what i use from collections import defaultdict A_j_dict = defaultdict(float) for A_item in TG: A_j_dict[A_item[1]] += A_item[3] Although this works fine, I really feel that it is a brute force / hacking method and unmaintainable in the case we want to add more variables or parameters. Are there any math equation parsers you'd recommend? Side Note: These equations are used to model travel. Currently I use excel to solve a lot of these equations; and I find that process to be daunting. I'd rather move to python where it pulls the data directly from our database (postgres) and outputs the results into the database. All that is figured out. I'm just struggling with evaluating the equations themselves. Thanks :)

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• DAL Layer : EF 4.0 or Normal Data access layer with Stored Procedure

  - by Harryboy

  Hello Experts, Application : I am working on one mid-large size application which will be used as a product, we need to decide on our DAL layer. Application UI is in Silverlight and DAL layer is going to be behind service layer. We are also moving ahead with domain model, so our DB tables and domain classes are not having same structure. So patterns like Data Mapper and Repository will definitely come into picture. I need to design DAL Layer considering below mentioned factors in priority manner Speed of Development with above average performance Maintenance Future support and stability of the technology Performance Limitation : 1) As we need to strictly go ahead with microsoft, we can not use NHibernate or any other ORM except EF 4.0 2) We can use any code generation tool (Should be Open source or very cheap) but it should only generate code in .Net, so there would not be any licensing issue on per copy basis. Questions I read so many articles about EF 4.0, on outset it looks like that it is still lacking in features from NHibernate but it is considerably better then EF 1.0 So, Do you people feel that we should go ahead with EF 4.0 or we should stick to ADO .Net and use any code geneartion tool like code smith or any other you feel best Also i need to answer questions like what time it will take to port application from EF 4.0 to ADO .Net if in future we stuck up with EF 4.0 for some features or we are having serious performance issue. In reverse case if we go ahead and choose ADO .Net then what time it will take to swith to EF 4.0 Lastly..as i was going through the article i found the code only approach (with POCO classes) seems to be best suited for our requirement as switching is really easy from one technology to other. Please share your thoughts on the same and please guide on the above questions

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• 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.

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• How to extract paragaph and selected lines with Perl

  - by neversaint

  I have a text that looks like this. What I want to do is to extract the whole paragraph under the section "Aceview summary" until the line that starts with "Please quote". extract the line that starts with "The closest human gene". And store them into array with two elements. However I am stuck with the following script logic. What's the right way to achieve that? #!/usr/bin/perl -w my $INFILE_file_name = $file; # input file name open ( INFILE, '<', $INFILE_file_name ) or croak "$0 : failed to open input file $INFILE_file_name : $!\n"; my @allsum; while ( <INFILE> ) { chomp; my $line = $_; my @temp1 = (); if ( $line =~ /^ AceView summary/ ) { print "$line\n"; push @temp1, $line; } elsif( $line =~ /Please quote/) { push @allsum, [@temp1]; @temp1 = (); } } close ( INFILE ); # close input file

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• RANDOM Number Generation in C

  - by CVS-2600Hertz-wordpress-com

  Recently i have begun development of a simple game. It is improved version of an earlier version that i had developed. Large part of the game's success depends on Random number generation in different modes: MODE1 - Truly Random mode myRand(min,max,mode=1); Should return me a random integer b/w min & max. MODE2 - Pseudo Random : Token out of a bag mode myRand(min,max,mode=2); Should return me a random integer b/w min & max. Also should internally keep track of the values returned and must not return the same value again until all the other values are returned atleast once. MODE3 - Pseudo Random : Human mode myRand(min,max,mode=3); Should return me a random integer b/w min & max. The randomisation ought to be not purely mathematically random, rather random as user perceive it. How Humans see RANDOM. * Assume the code is time-critical (i.e. any performance optimisations are welcome) * Pseudo-code will do but an implementation in C is what i'm looking for. * Please keep it simple. A single function should be sufficient (thats what i'm looking for) Thank You

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• How large a role does subjectiveness play in programming?

  - by Bob

  I often read about the importance of readability and maintainability. Or, I read very strong opinions about which syntax features are bad or good. Or discussions about the values of certain paradigms, like OOP. Aside from that, this same question floats about in my mind whenever I read debates on SO or Meta about subjective questions. Or read questions about best practices and sometimes find myself or others disagreeing. What role does subjectiveness play within the programming realm? Sometimes I think it plays a large role. Software developers are engineers in a way, but also people. A large part of programming is dealing with code that's human readable. This is very different from Math or Physics or other disciplines with very exact and structured rules. Here the exact structure and rules are largely up in the air, changeable on a whim, and hence the amount of languages in existence. And one person may find one language very readable, and another person may find their own language the most comforting. The same with practices. One person may not like certain accepted practices. I myself find splitting classes into different files very unreadable, for instance. But, I can't say rules haven't helped in general. Certain practices have and do make life easier. And new languages have given rise to syntax and structure that make life easier. There's certainly been a progression towards code that is easier to read and maintain even given a largely diverse group of people. So maybe these things aren't as subjective as I thought. It reminds me, in a way, of UI design. Certainly it's subjective, but then there's an entire discipline involved in crafting good UI and it tends to work. Is there something non-subjective about the ideas behind maintainability, readability, and other best practices? Is there something tangible to grasp when one develops a new language or thinks of new practices?

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• Using Hidden Markov Model for designing AI mp3 player

  - by Casper Slynge

  Hey guys. Im working on an assignment, where I want to design an AI for a mp3 player. The AI must be trained and designed with the use of a HMM method. The mp3 player shall have the functionality of adapting to its user, by analyzing incoming biological sensor data, and from this data the mp3 player will choose a genre for the next song. Given in the assignment is 14 samples of data: One sample consist of Heart Rate, Respiration, Skin Conductivity, Activity and finally the output genre. Below is the 14 samples of data, just for you to get an impression of what im talking about. Sample HR RSP SC Activity Genre S1 Medium Low High Low Rock S2 High Low Medium High Rock S3 High High Medium Low Classic S4 High Medium Low Medium Classic S5 Medium Medium Low Low Classic S6 Medium Low High High Rock S7 Medium High Medium Low Classic S8 High Medium High Low Rock S9 High High Low Low Classic S10 Medium Medium Medium Low Classic S11 Medium Medium High High Rock S12 Low Medium Medium High Classic S13 Medium High Low Low Classic S14 High Low Medium High Rock My time of work regarding HMM is quite low, so my question to you is if I got the right angle on the assignment. I have three different states for each sensor: Low, Medium, High. Two observations/output symbols: Rock, Classic In my own opinion I see my start probabilities as the weightened factors for either a Low, Medium or High state in the Heart Rate. So the ideal solution for the AI is that it will learn these 14 sets of samples. And when a users sensor input is received, the AI will compare the combination of states for all four sensors, with the already memorized samples. If there exist a matching combination, the AI will choose the genre, and if not it will choose a genre according to the weightened transition probabilities, while simultaniously updating the transition probabilities with the new data. Is this a right approach to take, or am I missing something ? Is there another way to determine the output probability (read about Maximum likelihood estimation by EM, but dont understand the concept)? Best regards, Casper

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• What is the best anti-crack scheme for your trial or subscription software?

  - by gmatt

  Writing code takes time and effort and just like any other human being we need to live by making an income (save for the few that are actually self sustainable.) Here are 3 general schemes to make a living: Independent developers can offer a trial then purchase scheme. An alternative is an open source base application with pay extensions. A last (probably least popular with customers) scheme is to enforce some kind of subscription. Then the price of the software pales in comparison to the long term subscription fees. So, my question would be a hypothetical one. Suppose that you invest thousands of hours into developing an application. Now suppose you can choose any one of the three options to make a living off this application--or any other option you want--and suppose you have a very real fear of loosing 80% of your revenue to a cracked version if one can be made. To be clear this application does not require the internet to perform all its useful functions, that is, your application is a prime candidate to be a cracked release on some website. Which option would you feel most comfortable with defending yourself against this possible situation and briefly describe why this option would be the best.

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• INSERT INTO sql server error : invalid object name

  - by thormayer

  I have a problem with some statement on SQL SERVER the error I get is that I have an invalid object name 'TBL_VIDEOS' INSERT INTO TBL_VIDEOS ( TBL_VIDEOS.ID, TBL_VIDEOS.TITLE, TBL_VIDEOS.V_DESCRIPTION, TBL_VIDEOS.UPLOAD_DATE, TBL_VIDEOS.V_VIEWS, TBL_VIDEOS.USERNAME, TBL_VIDEOS.RATING, TBL_VIDEOS.V_SOURCE, TBL_VIDEOS.FLAG ) VALUES ('Z8MTRH3LmTVm', 'Why Creativity is the New Economy', 'Dr Richard Florida, one of the world&#39;s leading experts on economic competitiveness, demographic trends and cultural and technological innovation shows how developing the full human and creative capabilities of each individual, combined with institutional supports such as commercial innovation and new industry, will put us back on the path to economic and social prosperity. Listen to the podcast of the full event including audience Q&amp;A: http://www.thersa.org/events/audio-and-past-events/2012/why-creativity-is-the-new-economy Our events are made possible with the support of our Fellowship. Support us by donating or applying to become a Fellow. Donate: http://www.thersa.org/support-the-rsa Become a Fellow: http://www.thersa.org/fellowship/apply', CURRENT_TIMESTAMP, 0, 1, 0, 'http://www.youtube.com/watch?v=VPX7gowr2vE&feature=g-all-u' ,0) and I wonder what i've done wrong ? (btw, the error refer to line 1.. guess its the table name.. but it correct!

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• Best strategy for moving data between physical tiers in ASP.net

  - by Pete Lunenfeld

  Building a new ASP.net application, and planning to separate DB, 'service' tier and Web/UI tier into separate physical layers. What is the best/easiest strategy to move serialized objects between the service tier and the UI tier? I was considering serializing POCOs into JSON using simple ASP.net pages to serve the middle tier. Meaning that the UI/Web tier will request data from a (hidden to the outside user) web server that will return a JSON string. This kind of JSON 'emitter' seems easily testable. It also seems easily compressible for efficiently moving data over the WAN between tiers. I know that some folks use .asmx webservices for this kind of task, but this seems like there is excess overhead with SOAP, and the package is not as human readable (testable) as POCOs serialized as JSON. Others are using more complex technology like WCF which we have never used. Does anyone have advice for choosing a method for moving data/objects between the data (db) tier and the web (UI) tier over the WAN using .net technologies? Thanks!!!

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• iphone crash log with dSym not loading debug information

  - by AngeDeLaMort

  Hello, I was trying to see why my application crashed on the device (iPhone) using the dSym generated along the executable (in ad hoc), but I don't know why, there isn't any useful information. It seems that "Organizer" is able to find the appropriate dSym and translate some data into more readable one, but when it comes to my application, I just have an address. Since I know how to reproduce it, I've tried to setup my build so it can help me in the future. So, I've tried to find if I had all the proper flags set int the project build properties and everything seems fine. So after doing some research, it seems that all information are stripped during link time and the dSym seems completely useless. I've played with some flags, but nothing changed. So, is there something special to do in order to get the crash file human readable? Or is it impossible in the ad hoc setting? The closest thing near to work that I've done was to build a debug version and look up the address in it. At least it seems to give the right file. So, I made a sample app and here what I have: (the line I want is #4): Thread 0 Crashed: 0 libobjc.A.dylib 0x00003ebc objc_msgSend + 20 1 UIKit 0x0005c970 -[UIView dealloc] + 60 2 UIKit 0x0005c840 -[UIImageView dealloc] + 76 3 CoreFoundation 0x0003963a -[NSObject release] + 28 4 MyApplication 0x000046a6 0x1000 + 13990 5 UIKit 0x00069750 -[UIViewController view] + 44 6 MyApplication 0x000053fa 0x1000 + 17402 The crash is made using 2 successive releases on an object. Thanks in advance.

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• How to sort a date array in PHP

  - by Click Upvote

  I have an array in this format: Array ( [0] => Array ( [28th February, 2009] => 'bla' ) [1] => Array ( [19th March, 2009] => 'bla' ) [2] => Array ( [5th April, 2009] => 'bla' ) [3] => Array ( [19th April, 2009] => 'bla' ) [4] => Array ( [2nd May, 2009] => 'bla' ) ) I want to sort them out in the ascending order of the dates (based on the month, day, and year). What's the best way to do that? Originally the emails are being fetched in the MySQL date format, so its possible for me to get the array in this state: Array [ ['2008-02-28']='some text', ['2008-03-06']='some text' ] Perhaps when its in this format, I can loop through them, remove all the '-' (hyphen) marks so they are left as integars, sort them using array_sort() and loop through them yet again to sort them? Would prefer if there was another way as I'd be doing 3 loops with this per user. Thanks. Edit: I could also do this: $array[$index]=array('human'=>'28 Feb, 2009', 'db'=>'20080228', 'description'=>'Some text here'); But using this, would there be any way to sort the array based on the 'db' element alone? Edit 2: Updated initial var_dump

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• CMYK + CMYK = ? CMYK / 2 = ?

  - by Pete

  Suppose there are two colors defined in CMYK: color1 = 30, 40, 50, 60 color2 = 50, 60, 70, 80 If they were to be printed what values would the resulting color have? color_new = min(cyan1 + cyan2, 100), min(magenta1 + magenta2, 100), min(yellow1 + yellow2, 100), min(black1 + black2, 100)? Suppose there is a color defined in CMYK: color = 40, 30, 30, 100 It is possible to print a color at partial intensity, i.e. as a tint. What values would have a 50% tint of that color? color_new = cyan / 2, magenta / 2, yellow / 2, black / 2? I'm asking this to better understand the "tintTransform" function in PDF Reference 1.7, 4.5.5 Special Color Spaces, DeviceN Color Spaces Update: To better clarify: I'm not entirely concerned with human perception or how the CMYK dyies react to the paper. If someone specifies 90% tint which, when printed, looks like full intensity colorant, that's ok. In other words, if I asking how to compute 50% of cmyk(40, 30, 30, 100) I'm asking how to compute the new values, regardless of whether the result looks half-dark or not. Update 2: I'm confused now. I checked this in InDesign and Acrobat. For example Pantone 3005 has CMYK 100, 34, 0, 2, and its 25% tint has CMYK 25, 8.5, 0, 0.5. Does it mean I can "monkey around in a linear way"?

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• Passing data between ViewControllers versus doing local Fetch in each VC

  - by Tofrizer

  Hi All, I'm developing an iPhone app using Core Data and I'm looking for some general advice and recommendations on whether its acceptable to pass data between ViewControllers versus doing a local fetch in each ViewController as you navigate to it. Ordinarily I would say it all depends on various factors (e.g. performance etc) but the passing data approach is so prevalent in my app and I'm spooked by all the stories about Apple rejecting apps because of not conforming to their standard guidelines. So let me put another way -- is it non-standard to pass data between VC's? The reason I pass data so much is because each ViewController is just another view on to data present in my object model / graph. Once I have a handle on my first object in the first view controller (which I of course do have to fetch), I can use the existing object composition / relationships to drill down into the next level of detail into data and so I just pass these objects to the next VC. Separately, one possible downside with this passing-data-to-each-VC approach is I don't benefit from (what I perceive to be) the optimisation/benefits that NSFetchedResultsController provides in terms of efficient memory usage and section handling. My app is read-only but I do have one table with 5000 rows and I'm curious if I am missing out on NSFetchedResultsController benefits. Any thoughts on this as well? Can I somehow still benefit from NSFetchedResultsController goodness without having to do a full fetch (as I would have already passed in the data from my previous VC)? Thanks a lot.

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• What is faster with PictureBox? Many small redraws or complete redraw.

  - by kornelijepetak

  I have a PictureBox (WinMobile 6 WinForm) on which I draw some images. There is a background image that goes in the background and it does not change. However objects that are drawn on the picturebox are moving during the application so I need to refresh the background. Since items that are redrawn fill from 50% to 80% of the surface, the question is which of the two is faster: 1) Redraw only parts of the background image that have been changed (previous+next location of the moving object). 2) Redraw complete background and then draw all the objects in their current position. Now, the reason for asking is because I am not sure how much of processor power is needed for a single drawImage operation and what are the time consuming factors. I am aware if there is almost complete coverage of the background, it would be stupid to redraw portions of it, because by drawing portions I will have drawn the complete picture. But since sometimes only half of the image had changed (some objects remained in their old position), it may (perhaps) be benefitial to redraw only those regions. But I need your insight on this... Thanks.

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• What is the easiest way to read wav-files using Python [summary]?

  - by Roman

  I want to use Python to access a wav-file and write its content in a form which allows me to analyze it (let's say arrays). I heard that "audiolab" is a suitable tool for that (it transforms numpy arrays into wav and vica versa). I have installed the "audiolab" but I had a problem with the version of numpy (I could not "from numpy.testing import Tester"). I had 1.1.1. version of numpy. I have installed a newer version on numpy (1.4.0). But then I got a new set of errors: Traceback (most recent call last): File "test.py", line 7, in import scikits.audiolab File "/usr/lib/python2.5/site-packages/scikits/audiolab/init.py", line 25, in from pysndfile import formatinfo, sndfile File "/usr/lib/python2.5/site-packages/scikits/audiolab/pysndfile/init.py", line 1, in from _sndfile import Sndfile, Format, available_file_formats, available_encodings File "numpy.pxd", line 30, in scikits.audiolab.pysndfile._sndfile (scikits/audiolab/pysndfile/_sndfile.c:9632) ValueError: numpy.dtype does not appear to be the correct type object I gave up to use audiolab and thought that I can use "wave" package to read in a wav-file. I asked a question about that but people recommended to use scipy instead. OK, I decided to focus on scipy (I have 0.6.0. version). But when I tried to do the following: from scipy.io import wavfile x = wavfile.read('/usr/share/sounds/purple/receive.wav') I get the following: Traceback (most recent call last): File "test3.py", line 4, in <module> from scipy.io import wavfile File "/usr/lib/python2.5/site-packages/scipy/io/__init__.py", line 23, in <module> from numpy.testing import NumpyTest ImportError: cannot import name NumpyTest So, I gave up to use scipy. Can I use just wave package? I do not need much. I just need to have content of wav-file in human readable format and than I will figure out what to do with that.

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• Which version of Grady Booch's OOA/D book should I buy?

  - by jackj

  Grady Booch's "Object-Oriented Analysis and Design with Applications" is available brand new in both the 2nd edition (1993) and the 3rd edition (2007), while many used copies of both editions are available. Here are my concerns: 1) The 2nd edition uses C++: given that I just finished reading my first two C++ books (Accelerated C++ and C++ Primer) I guess practical tips can only help, so the 2nd edition is probably best (I think the 3rd edition has absolutely no code). On the other hand, the C++ books I read insist on the importance of using standard C++, whereas Booch's 2nd edition was published before the 1998 standard. 2) The 2nd edition is shorter (608 pages vs. 720) so, I guess, it will be slightly easier to get through. 3) The 3rd edition uses UML 2.0, whereas the 2nd edition is pre-UML. Some reviews say that the notation in the 2nd edition is close enough to UML, so it doesn't matter, but I don't know if I should be worrying about this or not. 4) The 2nd edition is available in good-shape used copies for considerably less than what the 3rd one goes for. Given all the above factors, do you think I should buy the 2nd or the 3rd edition? Recommendations on other books are also welcome but I would prefer it if whoever answers has read at least one of the versions of Booch's book (preferably both!). I have already bought but not read GoF and Riel's books. I also know that I should practice a lot with real-life code. Thanks.

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• Perl: how to pretty-print time duration

  - by sds

  How do I pretty print time duration in perl? The only thing I could come up with so far is my $interval = 1351521657387 - 1351515910623; # milliseconds my $duration = DateTime::Duration->new( seconds => POSIX::floor($interval/1000) , nanoseconds => 1000000 * ($interval % 1000), ); my $df = DateTime::Format::Duration->new( pattern => '%Y years, %m months, %e days, ' . '%H hours, %M minutes, %S seconds, %N nanoseconds', normalize => 1, ); print $df->format_duration($duration); which results in 0 years, 00 months, 0 days, 01 hours, 35 minutes, 46 seconds, 764000000 nanoseconds This is no good for me for the following reasons: I don't want to see "0 years" (space waste) &c and I don't want to remove "%Y years" from the pattern (what if I do need years next time?) I know in advance that my precision is only milliseconds, I don't want to see the 6 zeros in the nanoseconds part. I care about prettiness/compactness/human readability much more than about precision/machine readability. I.e., I want to see something like "1.2 years" or "3.22 months" or "7.88 days" or "5.7 hours" or "75.5 minutes" (or "1.26 hours, whatever looks better to you) or "24.7 seconds" or "133.7 milliseconds" &c (similar to how R prints difftime)

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