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  • Source-to-source compiler framework wanted

    - by cheungcc_2000
    Dear all, I used to use OpenC++ (http://opencxx.sourceforge.net/opencxx/html/overview.html) to perform code generation like: Source: class MyKeyword A { public: void myMethod(inarg double x, inarg const std::vector<int>& y, outarg double& z); }; Generated: class A { public: void myMethod(const string& x, double& y); // generated method below: void _myMehtod(const string& serializedInput, string& serializedOutput) { double x; std::vector<int> y; // deserialized x and y from serializedInput double z; myMethod(x, y, z); } }; This kind of code generation directly matches the use case in the tutorial of OpenC++ (http://www.csg.is.titech.ac.jp/~chiba/opencxx/tutorial.pdf) by writing a meta-level program for handling "MyKeyword", "inarg" and "outarg" and performing the code generation. However, OpenC++ is sort of out-of-date and inactive now, and my code generator can only work on g++ 3.2 and it triggers error on parsing header files of g++ of higher version. I have looked at VivaCore, but it does not provide the infra-structure for compiling meta-level program. I'm also looking at LLVM, but I cannot find documentation that tutor me on working out my source-to-source compilation usage. I'm also aware of the ROSE compiler framework, but I'm not sure whether it suits my usage, and whether its proprietary C++ front-end binary can be used in a commercial product, and whether a Windows version is available. Any comments and pointers to specific tutorial/paper/documentation are much appreciated.

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  • How to prove writing specifications beats code cowboys?

    - by Andrew Grant
    So I have a problem. Or rather my friend has a problem, since I would never write about my company on an internet forum. At my friend's company specification writing is, shall we say, a little underused. There's a deeply ingrained culture of writing code first and asking questions later, whether it's for a library routine or a new tool to inflict on their long suffering designers. This of course leads to situations where functionality is partially correct, incorrect, or just completely missing ("oh, just save before trying anything you may want to undo"). This usually results in a loss of productivity for those poor designers, or beta periods where bug-fixing is largely spent implementing things correctly. My friend's found his suggestions of writing (and testing against) specifications to be generally well received. Most of his colleagues have embraced the wonderful feeling of discovering false-assumptions on paper, instead of at 11pm on a Sunday in the middle of beta. Viva La Revolution! However there are a few who poo-poo anything that stands between their task and a keyboard. They laugh at the thought of actually designing anything, and write code with merry abandon. Mostly these are senior, long employed developers, reluctant to "waste time". The problem is that this second group of heretics invariably produce things (or at least something) quicker than the first. Subsequently this becomes justification along the lines of "It's pointless to write specifications for something as simple as an image resizer! Oh and those bugs where width!=height or the image uses RLE just need a few tweaks". And now the question :) Other than saying "told you so" at the end of a project, what are some good short-term ways to demonstrate how the practice of writing functional or technical specifications leads to better software in the long run? Cheers!

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  • Storing a digital signature for bookings on a web based system

    - by Duncan
    I have a web based bookings system built for a UK higher education client to allow students to sign out equipment (laptops, camera's etc). It's been in use successfully for a couple of years, in the current workflow equipment is collected and the booking is printed, signed by the student and kept until the equipment is returned. They are emailed a pdf copy of the booking and reminders if equipment is outstanding. Students can login and prebook equipment using their university LDAP credentials, the booking is then authorised by staff for later collection, but can also walk in and have equipment booked out by staff. They would like to remove the signed paper part of the process and replace this with some sort of digital signature. The suggestion was a graphics tablet but with a web based system this would require a local software package and in my view be impractical. My thought is that students would enter their LDAP username and password upon collection of the equipment, verifying their identity and effectively digitally signing the booking. My question is what would be best to store as a signature or whether to simply authenticate the user and use a boolean flag to indicate that this has been done could be deemed sufficient?

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  • Publishing toolchain

    - by Marcelo de Moraes Serpa
    Hello all, I have a book project which I'd like to start sooner than later. This would follow an agile-like publishing workflow, i.e: publish early and often. It is meant to be self-publsihed by me and I'm not really looking to paper-publish it, even though we never know. If I weren't a geek, I'd probably have already started writting in Word or any other WYSIWYG tool and just export to PDF. However, we know it is not the best solution, and emacs rules my text-editing life, so, the output format should be as simple as possible and be text-based. I've thought about the following options: 1) Use orgmode and export to PDF; 2) Use markdown mode and export to PDF; 3) Use something similar to what the guys @ Pragmatic Progammers do: A XML + XSLT + LaTeX. More complex, but much more control over the style. Any other ideas / references ? I want to start writting as soon as possible. In fact, I already have a draft in an org-formatted file. However, I do want to have and use the full power of LaTex later on to format it the way I want and make it look fabulous :) Thanks in advance, Marcelo.

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  • Raytracing (LoS) on 3D hex-like tile maps

    - by herenvardo
    Greetings, I'm working on a game project that uses a 3D variant of hexagonal tile maps. Tiles are actually cubes, not hexes, but are laid out just like hexes (because a square can be turned to a cube to extrapolate from 2D to 3D, but there is no 3D version of a hex). Rather than a verbose description, here goes an example of a 4x4x4 map: (I have highlighted an arbitrary tile (green) and its adjacent tiles (yellow) to help describe how the whole thing is supposed to work; but the adjacency functions are not the issue, that's already solved.) I have a struct type to represent tiles, and maps are represented as a 3D array of tiles (wrapped in a Map class to add some utility methods, but that's not very relevant). Each tile is supposed to represent a perfectly cubic space, and they are all exactly the same size. Also, the offset between adjacent "rows" is exactly half the size of a tile. That's enough context; my question is: Given the coordinates of two points A and B, how can I generate a list of the tiles (or, rather, their coordinates) that a straight line between A and B would cross? That would later be used for a variety of purposes, such as determining Line-of-sight, charge path legality, and so on. BTW, this may be useful: my maps use the (0,0,0) as a reference position. The 'jagging' of the map can be defined as offsetting each tile ((y+z) mod 2) * tileSize/2.0 to the right from the position it'd have on a "sane" cartesian system. For the non-jagged rows, that yields 0; for rows where (y+z) mod 2 is 1, it yields 0.5 tiles. I'm working on C#4 targeting the .Net Framework 4.0; but I don't really need specific code, just the algorithm to solve the weird geometric/mathematical problem. I have been trying for several days to solve this at no avail; and trying to draw the whole thing on paper to "visualize" it didn't help either :( . Thanks in advance for any answer

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  • C#, sometimes I could flush down my boss the toilet [closed]

    - by msfanboy
    Hello all, I got a paper of instructions from my boss. One of the instructions is in this order: Extend the method GetProductIdBy with theShipmentDate Overload the method GetProductIdBy without theShipmentDate This is the Method I speak about: ...and theShipmentDate is a DateTime variable public IProduct GetProductIdBy(string productID) { ... return product; } You know what I did? this - public IProduct GetProductIdBy(string productID, DateTime theShipmentDate ) { ... return product; } You know what my boss said? The above is wrong! I asked him how can I overload a method without a parameter like theShipmentDate ??? That makes no sense, he said that reason in because of the subversion repository... what the fuck?? But he did not tell me whats really right I would have to find out for myself... he just didnt tell me and I am sick of asking him every crap if he cant express himself properly. How would you manage his instruction?

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  • 3x3 Sobel operator and gradient features

    - by pithyless
    Reading a paper, I'm having difficulty understanding the algorithm described: Given a black and white digital image of a handwriting sample, cut out a single character to analyze. Since this can be any size, the algorithm needs to take this into account (if it will be easier, we can assume the size is 2^n x 2^m). Now, the description states given this image we will convert it to a 512-bit feature (a 512-bit hash) as follows: (192 bits) computes the gradient of the image by convolving it with a 3x3 Sobel operator. The direction of the gradient at every edge is quantized to 12 directions. (192 bits) The structural feature generator takes the gradient map and looks in a neighborhood for certain combinations of gradient values. (used to compute 8 distinct features that represent lines and corners in the image) (128 bits) Concavity generator uses an 8-point star operator to find coarse concavities in 4 directions, holes, and lagrge-scale strokes. The image feature maps are normalized with a 4x4 grid. I'm for now struggling with how to take an arbitrary image, split into 16 sections, and using a 3x3 Sobel operator to come up with 12 bits for each section. (But if you have some insight into the other parts, feel free to comment :)

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  • How to setup matlabpool for multiple processors?

    - by JohnIdol
    I just setup a Extra Large Heavy Computation EC2 instance to throw it at my Genetic Algorithms problem, hoping to speed up things. This instance has 8 Intel Xeon processors (around 2.4Ghz each) and 7 Gigs of RAM. On my machine I have an Intel Core Duo, and matlab is able to work with my two cores just fine by runinng: matlabpool open 2 On the EC2 instance though, matlab only is capable of detecting 1 out of 8 processors, and if I try running: matlabpool open 8 I get an error saying that the ClusterSize is 1 since there's only 1 core on my CPU. True, there is only 1 core on each CPU, but I have 8 CPUs on the given EC2 instance! So the difference from my machine and the ec2 instance is that I have my 2 cores on a single processor locally, while the EC2 instance has 8 distinct processors. My question is, how do I get matlab to work with those 8 processors? I found this paper, but it seems related to setting up matlab with multiple EC2 instances (not related to multiple processors on the same instance, EC2 or not), which is not my problem. Any help appreciated!

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  • Variable-width inline underline effects in CSS

    - by sidereal
    I need to simulate the look of a typical paper form in CSS. It consists of a two-column table of fields. Each field consists of a field name (of variable width) followed by an underline that continues to the end of the column. The field might be populated, in which case there is some text centered above the line, or it may be blank. If that isn't clear, he's a rough idea in manky ASCII art: Name: _______Foo_______ Age: _____17______ Location: __Melbourne__ Handedness: _Left_ (except that the underline would continue under any text) To implement the underline without text, I assume I should use a border-bottom rather than a text-decoration: underline. Additionally, I need the bordered element to take up the full available space. Both of those argue for a block-level element. However, I can't find any way to get the block level element (either a div, an li, or a span set to display: block or inline-block) to remain on the same line as the label. As soon as I give it a width: 100%, it newlines. I've tried various combinations of floats, and I'm not inclined to do anything ridiculous with absolute positioning. Any recommendations?

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  • Bubble Breaker Game Solver better than greedy?

    - by Gregory
    For a mental exercise I decided to try and solve the bubble breaker game found on many cell phones as well as an example here:Bubble Break Game The random (N,M,C) board consists N rows x M columns with C colors The goal is to get the highest score by picking the sequence of bubble groups that ultimately leads to the highest score A bubble group is 2 or more bubbles of the same color that are adjacent to each other in either x or y direction. Diagonals do not count When a group is picked, the bubbles disappear, any holes are filled with bubbles from above first, ie shift down, then any holes are filled by shifting right A bubble group score = n * (n - 1) where n is the number of bubbles in the bubble group The first algorithm is a simple exhaustive recursive algorithm which explores going through the board row by row and column by column picking bubble groups. Once the bubble group is picked, we create a new board and try to solve that board, recursively descending down Some of the ideas I am using include normalized memoization. Once a board is solved we store the board and the best score in a memoization table. I create a prototype in python which shows a (2,15,5) board takes 8859 boards to solve in about 3 seconds. A (3,15,5) board takes 12,384,726 boards in 50 minutes on a server. The solver rate is ~3k-4k boards/sec and gradually decreases as the memoization search takes longer. Memoization table grows to 5,692,482 boards, and hits 6,713,566 times. What other approaches could yield high scores besides the exhaustive search? I don't seen any obvious way to divide and conquer. But trending towards larger and larger bubbles groups seems to be one approach Thanks to David Locke for posting the paper link which talks above a window solver which uses a constant-depth lookahead heuristic.

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  • Scaling Literate Programming?

    - by Tetha
    Greetings. I have been looking at Literate Programming a bit now, and I do like the idea behind it: you basically write a little paper about your code and write down as much of the design decisions, the code probably surrounding the module, the inner workins of the module, assumptions and conclusions resulting from the design decisions, potential extension, all this can be written down in a nice way using tex. Granted, the first point: it is documentation. It must be kept up-to-date, but that should not be that bad, because your change should have a justification and you can write that down. However, how does Literate Programming Scale to a larger degree? Overall, Literate Programming is still just text. Very human readable text, of course, but still text, and thus, it is hard to follow large systems. For example, I reworked large parts of my compiler to use and some magic to chain compile steps together, because some "x.register_follower(y); y.register_follower(z); y.register_follower(a);..." got really unwieldy, and changing that to x y z a made it a bit better, even though this is at its breaking point, too. So, how does Literate Programming scale to larger systems? Does anyone try to do that? My thought would be to use LP to specify components that communicate with each other using event streams and chain all of these together using a subset of graphviz. This would be a fairly natural extension to LP, as you can extract a documentation -- a dataflow diagram -- from the net and also generate code from it really well. What do you think of it? -- Tetha.

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  • An annoying printing issue with Crystal Reports 2008

    - by Xience
    A little background: I have an extremely annoying printing issue with crystal reports. My environment is crystal reports 2008 SP2 on Windows 7 (64bit), Visual studio 2008 and .net framework 3.5 with all the latest updates for everything. The report is designed basically to render a small shelf label of the size (40mm width and 20mm height). In crystal when I set the page size to the above mentioned values and set orientation to portrait and take a preview, everything is displayed as i expect it to be and issuing a print command, it prints absolutely correct. The problem: The problem comes when i print this report from my program (in vb.net), dynamically setting data to some text fields, the result is that crystal somehow changes the print orientation, NOT the paper orientation as in portrait or landscape. Instead of printing from top left towards the bottom right, it rotates the whole output at 90 degrees to the left and reduces everything so small that it is barely visible, although it prints everything out. I have tested it on Intermec PF8t and Zebra GK420d label printers and a whole bunch of laser printers, but with the above stated page settings the output is always the same. Another strange thing that i noticed while experimenting with page sizes if i switch to landscape mode, the print out is correct in its font sizes and positions but then the text gets truncated due to overflowing the page size. Can anyone help me with this. Does crystal has anything like its own print drivers or something. I have tried to ensure to the best of my abilities that it is not a printer driver problem.

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  • reconstructing a tree from its preorder and postorder lists.

    - by NomeN
    Consider the situation where you have two lists of nodes of which all you know is that one is a representation of a preorder traversal of some tree and the other a representation of a postorder traversal of the same tree. I believe it is possible to reconstruct the tree exactly from these two lists, and I think I have an algorithm to do it, but have not proven it. As this will be a part of a masters project I need to be absolutely certain that it is possible and correct (Mathematically proven). However it will not be the focus of the project, so I was wondering if there is a source out there (i.e. paper or book) I could quote for the proof. (Maybe in TAOCP? anybody know the section possibly?) In short, I need a proven algorithm in a quotable resource that reconstructs a tree from its pre and post order traversals. Note: The tree in question will probably not be binary, or balanced, or anything that would make it too easy. Note2: Using only the preorder or the postorder list would be even better, but I do not think it is possible. Note3: A node can have any amount of children. Note4: I only care about the order of siblings. Left or right does not matter when there is only one child.

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  • OpenGL - drawing 2D polygons shapes with texture

    - by plonkplonk
    I am trying to make a few effects in a C+GL game. So far I draw all my sprites as a quad, and it works. However, I am trying to make a large ring appear at times, with a texture following that ring, as it takes less memory than a quad with the ring texture inside. The type of ring I want to make is not a round-shaped GL mesh ring (the "tube" type) but a "paper" 2D ring. That way I can modify the "width" of the ring, getting more of the effect than a simple quad+ring texture. So far all my attempts have been...kind of ridiculous, as I don't understand GL's coordinates too well (and I can't really understand the available documentation...I am just a designer with no coder help or background. A n00b, basically). glBegin(GL_POLYGON); for(i = 0;i < 360; i += 10){ glTexCoord2f(0, 0); glVertex2f(Cos(i)*(H-10),Sin(i)H); glTexCoord2f(0, HP); glVertex2f(Sin(i)(H-10),Cos(i)*(H-10)); glTexCoord2f(WP, HP); glVertex2f(Cos(i)H,Sin(i)(H-10)); glTexCoord2f(WP, 0); glVertex2f(Sin(i)*H,Cos(i)*H); } glEnd(); This is my last attempt, and it seems to generate a "sunburst" from the right edge of the circle instead of a ring. It's an amusing effect but definitely not what I want. Other results included the circle looking exactly the same as the quad textured (aka drawing a sprite literally) or something that looked like a pop-art filter, by working on this train of thought. Seems like my logic here is entirely flawed, so, what would be the easiest way to obtain such a ring? No need to reply in code, just some guidance for a non-math-skilled user...

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  • How does real-time collaboration with multiple clients work in a system using operation transformati

    - by Saikat Chakrabarti
    I just finished reading High-Latency, Low-Bandwidth Windowing in the Jupiter Collaboration System and I mostly followed everything until part 6: global consistency. This part describes how the system described in the paper can be extended to accomodate for multiple clients connected to the server. However, the explanation is very short and essentially says the system will work if the central server merely forwards client messages to all the other clients. I don't really understand how this works though. What state vector would be sent in the message that is sent to all the other clients? Does the server maintain separate state vectors for each client? Does it maintain a separate copy of the widgets locally for each client? The simple example I can think of is this setup: imagine client A, server, and client B with client A and client B both connected to the server. To start, all three have the state object "ABCD". Then, client A sends the message "insert character F at position 0" at the same time client B sends the message "insert character G at position 0" to the server. It seems like simply relaying client A's message to client B and vice versa doesn't actually handle this case. So what exactly does the server do?

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  • Big Nerd Ranch's Android Bootcamp - worth it?

    - by Matt Luongo
    At work, I've been told that I must, before the end of the year, get a certification. The shop is Microsoft heavy, and I'm not. That's why I was excited when I suggested something in support of Android development, and they agreed. Before I go any further, I should say that I don't know what I think about the whole certification question. Frankly, though, I need to do this, regardless of whether I think certification in general is particularly appealing to clients. I realize that the technology is fairly accessible without all this expensive process- but I'd rather focus on Android than, say, getting some MC* scrap of paper. I don't know of any actual Android certification. Instead, I was thinking that the best regarded Android training in the industry should suffice. I've looked into Big Nerd Ranch's Android Bootcamp, and it looks promising. I live in Atlanta, which is a boon. Given that my Java skills are good, does this seem like a decent course? Or is there a better known training program that I should look into?

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  • MySql Geospatial bug..?

    - by ShaChris23
    This question is for Mysql geospatial-extension experts. The following query doesn't the result that I'm expecting: create database test_db; use test_db; create table test_table (g polygon not null); insert into test_table (g) values (geomfromtext('Polygon((0 5,5 10,7 8,2 3,0 5))')); insert into test_table (g) values (geomfromtext('Polygon((2 3,7 8,9 6,4 1,2 3))')); select X(PointN(ExteriorRing(g),1)), Y(PointN(ExteriorRing(g),1)), X(PointN(ExteriorRing(g),2)), Y(PointN(ExteriorRing(g),2)), X(PointN(ExteriorRing(g),3)), Y(PointN(ExteriorRing(g),3)), X(PointN(ExteriorRing(g),4)), Y(PointN(ExteriorRing(g),4)) from test_table where MBRContains(g,GeomFromText('Point(3 6)')); Basically we are creating 2 Polygons, and we are trying to use MBRContains to determine whether a Point is within either of the two polygons. Surprisingly, it returns both polygons! Point 3,6 should only exist in the first inserted polygon. Note that both polygons are tilted (once you draw the polygons on a piece of paper, you will see) How come MySql returns both polygons? I'm using MySql Community Edition 5.1.

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  • Working with ieee format numbers in ARM

    - by Jake Sellers
    I'm trying to write an ARM program that will convert an ieee number to a TNS format number. TNS is a format used by some super computers, and is similar to ieee but different. I'm trying to use several masks to place the three different "part" of the ieee number in separate registers so I can move them around accordingly. Here is my unpack subroutine: UnpackIEEE LDR r1, SMASK ;load the sign bit mask into r1 LDR r2, EMASK ;load the exponent mask into r2 LDR r3, GMASK ;load the significand mask into r3 AND r4, r0, r1 ;apply sign mask to IEEE and save into r4 AND r5, r0, r2 ;apply exponent mask to IEEE and save into r5 AND r6, r0, r3 ;apply significand mask to IEEE and save into r6 MOV pc, r14 ;return And here are the masks and number declarations so you can understand: IEEE DCD 0x40300000 ;2.75 decimal or 01000000001100000000000000000000 binary SMASK DCD 0x80000000 ;Sign bit mask EMASK DCD 0x7F800000 ;Exponent mask GMASK DCD 0x007FFFFF ;Significand mask When I step through with the debugger, the results I get are not what I expect after working through it on paper. EDIT: What I mean, is that after the subroutine runs, registers 4, 5, and 6 all remain 0. I can't figure out why the masks are not working. I think I do not fully understand how the number is being stored in the register or using the masks wrong. Any help appreciated. If you need more info just ask. EDIT: entry point: Very simple, just trying to get these subroutines working. ENTRY LDR r1, IEEE ;load IEEE num into r1 BL UnpackIEEE ;call unpack sub SWI SWI_Exit ;finish

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  • Interactive Web Collaboration Platform

    - by user1477586
    I am currently unsatisfied with most, if not all, web-based collaboration tools I've ever used. Examples of what I'm considering a "web-based collaboration tool" are TWiki, WebEx, etc. What I have in mind of developing is to develop my own. The target "market" is for software/hardware developers who will likely be working on separate projects linked by a common goal. Example: You work at a company who is designing a brand new printer. So, one man is working on the ink cartridge, another on the paper feed, one on the circuitry of the printer and one more is working on the drivers. What I would like to make (unless it already exists) is a website that, upon loading, presents the user with a web that has each project within it's own bubble, graphically. These bubbles would all be linked to the central bubble of "[Company Name]". Upon selecting an individual bubble the browser would focus and zoom in on that project bubble and expand more information (in bullets or with more affiliated bubbles) about subprojects, progress, setbacks, etc. Then, at a terminal "node" (i.e. a bubble with no sub-bubbles) a selection would then load a page with information relevant to that node. That's a lot of monologue. In short, I want to know how I might approach this. My background is with algorithmic use of Python and C++. I've never done interactive web design like this; though, I have gone through the W3C tutorials on HTML4/5. I'm willing to learn a new language I'm just wondering which language/set of languages seem(s) most appropriate for this project. Thanks, world, for imparting your knowledge to me. An example of what the start page might look like is:

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  • Is there a standard lexer/parser tool for Python?

    - by Salim Fadhley
    A volunteer job requires us to convert a large number of LaTeX documents into ePub format. It's a series of open-source fiction book which has so far only been produced only on paper via a print on demand service. We'd like to be able to offer the book to users of book-reader devices (such as Kindle) which require the ePub format for best results. Fortunately, ePub is a very simple format, however there's no trivial way for LaTeX to produce the XHTML outut required. We experimented with alternative LaTeX compilers (e.g. plastex) but in the end we figured that it would probably be a lot easier to simply write our own compiler which understands a tiny subset of the LaTeX language and compiles directly to XHTML / ePub. Previously I used a tool on Windows called GOLD. This allowed me to go directly from BNF grammars to a stub parser. It also alllowed me to implement the parser in any language I liked. (I'd choose Python). This product has to work on Linux, so I'm wondering if there's an equivalent toolchain that works as well under Ubutnu / Eclipse / Python. The idea is that we will take the grammar of TeX and just implement a teeny subset of that, but we do not want to spend a huge amount of time worrying about grammar and parsing. A parser generator would obviously save us a great deal of time. Sal UPDATE 1: Bonus marks for a solution with excellent documentation or tutorials.

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  • forks in C - exercise

    - by Zka
    I try to repeat and learn more advanced uses and options when cutting trees with forks in the jungle of C. But foolishly I find an example which should be very easy as I have worked with forks before and even written some code, but i can't understand it fully. Here comes : main() { if (fork() == 0) { if (fork() == 0) { printf("3"); } else if ((wait(NULL)) > 0) { printf("2"); } } else { if (fork() == 0) { printf("1"); exit(0); } if (fork() == 0) { printf("4"); } } printf("0"); return 0; } Possible solutions are : 3201040 3104200 1040302 4321000 4030201 1403020 where 2, 5 and 6 are correct answers. First of all, shouldn't there be four zeroes in the output? Second... How does one come to the solution at all? Been doing this on paper for almost an hour and I'm not even close to understanding why the given solution are more correct than the false ones (except for nr3 as it can't end with 2 since a 0 must follow). Anyone with his forks in check who can offer some good explanation?

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  • Writing fortran robust and "modern" code

    - by Blklight
    In some scientific environments, you often cannot go without FORTRAN as most of the developers only know that idiom, and there is lot of legacy code and related experience. And frankly, there are not many other cross-platform options for high performance programming ( C++ would do the task, but the syntax, zero-starting arrays, and pointers are too much for most engineers ;-) ). I'm a C++ guy but I'm stuck with some F90 projects. So, let's assume a new project must use FORTRAN (F90), but I want to build the most modern software architecture out of it. while being compatible with most "recent" compilers (intel ifort, but also including sun/HP/IBM own compilers) So I'm thinking of imposing: global variable forbidden, no gotos, no jump labels, "implicit none", etc. "object-oriented programming" (modules with datatypes + related subroutines) modular/reusable functions, well documented, reusable libraries assertions/preconditions/invariants (implemented using preprocessor statements) unit tests for all (most) subroutines and "objects" an intense "debug mode" (#ifdef DEBUG) with more checks and all possible Intel compiler checks possible (array bounds, subroutine interfaces, etc.) uniform and enforced legible coding style, using code processing tools C stubs/wrappers for libpthread, libDL (and eventually GPU kernels, etc.) C/C++ implementation of utility functions (strings, file operations, sockets, memory alloc/dealloc reference counting for debug mode, etc.) ( This may all seem "evident" modern programming assumptions, but in a legacy fortran world, most of these are big changes in the typical programmer workflow ) The goal with all that is to have trustworthy, maintainable and modular code. Whereas, in typical fortran, modularity is often not a primary goal, and code is trustworthy only if the original developer was very clever, and the code was not changed since then ! (i'm a bit joking here, but not much) I searched around for references about object-oriented fortran, programming-by-contract (assertions/preconditions/etc.), and found only ugly and outdated documents, syntaxes and papers done by people with no large-scale project involvement, and dead projects. Any good URL, advice, reference paper/books on the subject?

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  • What Scheme Does Ghuloum Use?

    - by Don Wakefield
    I'm trying to work my way through Compilers: Backend to Frontend (and Back to Front Again) by Abdulaziz Ghuloum. It seems abbreviated from what one would expect in a full course/seminar, so I'm trying to fill in the pieces myself. For instance, I have tried to use his testing framework in the R5RS flavor of DrScheme, but it doesn't seem to like the macro stuff: src/ghuloum/tests/tests-driver.scm:6:4: read: illegal use of open square bracket I've read his intro paper on the course, An Incremental Approach to Compiler Construction, which gives a great overview of the techniques used, and mentions a couple of Schemes with features one might want to implement for 'extra credit', but he doesn't mention the Scheme he uses in the course. Update I'm still digging into the original question (investigating options such as Petit Scheme suggested by Eli below), but found an interesting link relating to Gholoum's work, so I am including it here. [Ikarus Scheme](http://en.wikipedia.org/wiki/Ikarus_(Scheme_implementation)) is the actual implementation of Ghuloum's ideas, and appears to have been part of his Ph.D. work. It's supposed to be one of the first implementations of R6RS. I'm trying to install Ikarus now, but the configure script doesn't want to recognize my system's install of libgmp.so, so my problems are still unresolved. Example The following example seems to work in PLT 2.4.2 running in DrEd using the Pretty Big (require lang/plt-pretty-big) (load "/Users/donaldwakefield/ghuloum/tests/tests-driver.scm") (load "/Users/donaldwakefield/ghuloum/tests/tests-1.1-req.scm") (define (emit-program x) (unless (integer? x) (error "---")) (emit " .text") (emit " .globl scheme_entry") (emit " .type scheme_entry, @function") (emit "scheme_entry:") (emit " movl $~s, %eax" x) (emit " ret") ) Attempting to replace the require directive with #lang scheme results in the error message foo.scm:7:3: expand: unbound identifier in module in: emit which appears to be due to a failure to load tests-driver.scm. Attempting to use #lang r6rs disables the REPL, which I'd really like to use, so I'm going to try to continue with Pretty Big. My thanks to Eli Barzilay for his patient help.

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  • Cache consistency & spawning a thread

    - by Dave Keck
    Background I've been reading through various books and articles to learn about processor caches, cache consistency, and memory barriers in the context of concurrent execution. So far though, I have been unable to determine whether a common coding practice of mine is safe in the strictest sense. Assumptions The following pseudo-code is executed on a two-processor machine: int sharedVar = 0; myThread() { print(sharedVar); } main() { sharedVar = 1; spawnThread(myThread); sleep(-1); } main() executes on processor 1 (P1), while myThread() executes on P2. Initially, sharedVar exists in the caches of both P1 and P2 with the initial value of 0 (due to some "warm-up code" that isn't shown above.) Question Strictly speaking – preferably without assuming any particular CPU – is myThread() guaranteed to print 1? With my newfound knowledge of processor caches, it seems entirely possible that at the time of the print() statement, P2 may not have received the invalidation request for sharedVar caused by P1's assignment in main(). Therefore, it seems possible that myThread() could print 0. References These are the related articles and books I've been reading. (It wouldn't allow me to format these as links because I'm a new user - sorry.) Shared Memory Consistency Models: A Tutorial hpl.hp.com/techreports/Compaq-DEC/WRL-95-7.pdf Memory Barriers: a Hardware View for Software Hackers rdrop.com/users/paulmck/scalability/paper/whymb.2009.04.05a.pdf Linux Kernel Memory Barriers kernel.org/doc/Documentation/memory-barriers.txt Computer Architecture: A Quantitative Approach amazon.com/Computer-Architecture-Quantitative-Approach-4th/dp/0123704901/ref=dp_ob_title_bk

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  • The algorithm used to generate recommendations in Google News?

    - by Siddhant
    Hi everyone. I'm study recommendation engines, and I went through the paper that defines how Google News generates recommendations to users for news items which might be of their interest, based on collaborative filtering. One interesting technique that they mention is Minhashing. I went through what it does, but I'm pretty sure that what I have is a fuzzy idea and there is a strong chance that I'm wrong. The following is what I could make out of it :- Collect a set of all news items. Define a hash function for a user. This hash function returns the index of the first item from the news items which this user viewed, in the list of all news items. Collect, say "n" number of such values, and represent a user with this list of values. Based on the similarity count between these lists, we can calculate the similarity between users as the number of common items. This reduces the number of comparisons a lot. Based on these similarity measures, group users into different clusters. This is just what I think it might be. In Step 2, instead of defining a constant hash function, it might be possible that we vary the hash function in a way that it returns the index of a different element. So one hash function could return the index of the first element from the user's list, another hash function could return the index of the second element from the user's list, and so on. So the nature of the hash function satisfying the minwise independent permutations condition, this does sound like a possible approach. Could anyone please confirm if what I think is correct? Or the minhashing portion of Google News Recommendations, functions in some other way? I'm new to internal implementations of recommendations. Any help is appreciated a lot. Thanks!

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