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  • Pointer problem on external monitor

    - by Herby Pepper
    Pointer looks and work fine on laptop but when I connect external monitor it appears there as a shaking, square shape. Videos are not showing either. my laptop hp 2133: Graphic card: VIA Technologies, Inc. CN896/VN896/P4M900, Chrome 9 HC. System: Lubuntu 12.04 I think it is graphic problem but can't find drivers for my card and system. I do have xserver-xorg-video-openchrome and disper installed. I did not have that problem with Lubuntu 11.10. My problem is a bit like : Mouse pointer strange problem but it was not solved so I decided to post my question.

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  • lubridate error message 'incompatible method's when trying date arithmetic

    - by Sharon
    I'm trying to learn lubridate. The lubridate documentation shows: date <- ceiling_date(date, "month") - days(1) [1] "2010-05-31 UTC for date arithmetic. But if I try mytoday <- now() first_of_month <- floor_date(mytoday, "month") first_of_month_last_year <- first_of_month - years(1) to use date arithmetic to get the first of the month a year earlier I get an error message Warning message: Incompatible methods ("-.POSIXt", "Ops.ordered") for "-" Any ideas what I'm doing wrong? Thanks.

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  • Bitwise Operations -- Arithmetic Operations..

    - by RBA
    Hi, Can you please explain the below lines, with some good examples. A left arithmetic shift by n is equivalent to multiplying by 2n (provided the value does not overflow), while a right arithmetic shift by n of a two's complement value is equivalent to dividing by 2n(2 to the power n) and rounding toward negative infinity. If the binary number is treated as ones' complement, then the same right-shift operation results in division by 2n and rounding toward zero. Thankx..

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  • Uses of a C++ Arithmetic Promotion Header

    - by OlduvaiHand
    I've been playing around with a set of templates for determining the correct promotion type given two primitive types in C++. The idea is that if you define a custom numeric template, you could use these to determine the return type of, say, the operator+ function based on the class passed to the templates. For example: // Custom numeric class template <class T> struct Complex { Complex(T real, T imag) : r(real), i(imag) {} T r, i; // Other implementation stuff }; // Generic arithmetic promotion template template <class T, class U> struct ArithmeticPromotion { typedef typename X type; // I realize this is incorrect, but the point is it would // figure out what X would be via trait testing, etc }; // Specialization of arithmetic promotion template template <> class ArithmeticPromotion<long long, unsigned long> { typedef typename unsigned long long type; } // Arithmetic promotion template actually being used template <class T, class U> Complex<typename ArithmeticPromotion<T, U>::type> operator+ (Complex<T>& lhs, Complex<U>& rhs) { return Complex<typename ArithmeticPromotion<T, U>::type>(lhs.r + rhs.r, lhs.i + rhs.i); } If you use these promotion templates, you can more or less treat your user defined types as if they're primitives with the same promotion rules being applied to them. So, I guess the question I have is would this be something that could be useful? And if so, what sorts of common tasks would you want templated out for ease of use? I'm working on the assumption that just having the promotion templates alone would be insufficient for practical adoption. Incidentally, Boost has something similar in its math/tools/promotion header, but it's really more for getting values ready to be passed to the standard C math functions (that expect either 2 ints or 2 doubles) and bypasses all of the integral types. Is something that simple preferable to having complete control over how your objects are being converted? TL;DR: What sorts of helper templates would you expect to find in an arithmetic promotion header beyond the machinery that does the promotion itself?

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  • Arithmetic + and Bitwise OR

    - by Mohanavel
    Is there any difference between Arithmetic + and bitwise OR. For the below operation i used arithmetic operation, my friend told that this is wrong. In what way this is differing. uint a = 10; uint b = 20; uint arithmeticresult = a + b; uint bitwiseOR = a | b; Both the results are 30.

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  • Pointer to a C++ class member function as a global function's parameter?

    - by marcin1400
    I have got a problem with calling a global function, which takes a pointer to a function as a parameter. Here is the declaration of the global function: int lmdif ( minpack_func_mn fcn, void *p, int m, int n, double *x, double *fvec, double ftol) The "minpack_func_mn" symbol is a typedef for a pointer to a function, defined as: typedef int (*minpack_func_mn)(void *p, int m, int n, const double *x, double *fvec, int iflag ); I want to call the "lmdif" function with a pointer to a function which is a member of a class I created, and here is the declaration of this class function: int LT_Calibrator::fcn(void *p, int m, int n, const double *x, double *fvec,int iflag) I am calling a global function like this: info=lmdif(&LT_Calibrator::fcn, 0, m, n, x, fvec, ftol) Unfortunately, I get a compiler error, which says: "error C2664: 'lmdif' : cannot convert parameter 1 from 'int (__thiscall LT_Calibrator::* )(void *,int,int,const double *,double *,int)' to 'minpack_func_mn' 1 There is no context in which this conversion is possible" Is there any way to solve that problem?

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  • Name of the Countdown Numbers round problem - and algorithmic solutions?

    - by Dai
    For the non-Brits in the audience, there's a segment of a daytime game-show where contestants have a set of 6 numbers and a randomly generated target number. They have to reach the target number using any (but not necessarily all) of the 6 numbers using only arithmetic operators. All calculations must result in positive integers. An example: Youtube: Countdown - The Most Extraordinary Numbers Game Ever? A detailed description is given on Wikipedia: Countdown (Game Show) For example: The contentant selects 6 numbers - two large (possibilities include 25, 50, 75, 100) and four small (numbers 1 .. 10, each included twice in the pool). The numbers picked are 75, 50, 2, 3, 8, 7 are given with a target number of 812. One attempt is (75 + 50 - 8) * 7 - (3 * 2) = 813 (This scores 7 points for a solution within 5 of the target) An exact answer would be (50 + 8) * 7 * 2 = 812 (This would have scored 10 points exactly matching the target). Obviously this problem has existed before the advent of TV, but the Wikipedia article doesn't give it a name. I've also saw this game at a primary school I attended where the game was called "Crypto" as an inter-class competition - but searching for it now reveals nothing. I took part in it a few times and my dad wrote an Excel spreadsheet that attempted to brute-force the problem, I don't remember how it worked (only that it didn't work, what with Excel's 65535 row limit), but surely there must be an algorithmic solution for the problem. Maybe there's a solution that works the way human cognition does (e.g. in-parallel to find numbers 'close enough', then taking candidates and performing 'smaller' operations).

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  • bash and arithmetic comparison: double quotes or not?

    - by Martin
    when comparing two integers in bash, do we have to put double quotes ? In the official document http://tldp.org/LDP/abs/html/comparison-ops.html I can read that double quotes should appear every time... But what is the differences in the following examples: [ "$VAR" -eq "1" ] [ $VAR -eq "1" ] [ "$VAR" -eq 1 ] [ $VAR -eq 1 ] As I am curious, a took a look at Ubuntu init scripts in /etc/init.d and there are many usage of arithmetic comparison in it, at least [ "$VAR" -eq "1" ] and [ $VAR -eq 1 ] are used... but it seems no one really "knows" what is the official way to do it. Thanks !

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  • Will fixed-point arithmetic be worth my trouble?

    - by Thomas
    I'm working on a fluid dynamics Navier-Stokes solver that should run in real time. Hence, performance is important. Right now, I'm looking at a number of tight loops that each account for a significant fraction of the execution time: there is no single bottleneck. Most of these loops do some floating-point arithmetic, but there's a lot of branching in between. The floating-point operations are mostly limited to additions, subtractions, multiplications, divisions and comparisons. All this is done using 32-bit floats. My target platform is x86 with at least SSE1 instructions. (I've verified in the assembler output that the compiler indeed generates SSE instructions.) Most of the floating-point values that I'm working with have a reasonably small upper bound, and precision for near-zero values isn't very important. So the thought occurred to me: maybe switching to fixed-point arithmetic could speed things up? I know the only way to be really sure is to measure it, that might take days, so I'd like to know the odds of success beforehand. Fixed-point was all the rage back in the days of Doom, but I'm not sure where it stands anno 2010. Considering how much silicon is nowadays pumped into floating-point performance, is there a chance that fixed-point arithmetic will still give me a significant speed boost? Does anyone have any real-world experience that may apply to my situation?

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  • Fortran pointer as an argument to interface procedure

    - by icarusthecow
    Im trying to use interfaces to call different subroutines with different types, however, it doesnt seem to work when i use the pointer attribute. for example, take this sample code MODULE ptr_types TYPE, abstract :: parent INTEGER :: q END TYPE TYPE, extends(parent) :: child INTEGER :: m END TYPE INTERFACE ptr_interface MODULE PROCEDURE do_something END INTERFACE CONTAINS SUBROUTINE do_something(atype) CLASS(parent), POINTER :: atype ! code determines that this allocation is correct from input ALLOCATE(child::atype) WRITE (*,*) atype%q END SUBROUTINE END MODULE PROGRAM testpass USE ptr_types CLASS(child), POINTER :: ctype CALL ptr_interface(ctype) END PROGRAM This gives error Error: There is no specific subroutine for the generic 'ptr_interface' at (1) however if i remove the pointer attribute in the subroutine it compiles fine. Now, normally this wouldnt be a problem, but for my use case i need to be able to treat that argument as a pointer, mainly so i can allocate it if necessary. Any suggestions? Mind you I'm new to fortran so I may have missed something edit: forgot to put the allocation in the parents subroutine, the initial input is unallocated EDIT 2 this is my second attempt, with caller side casting MODULE ptr_types TYPE, abstract :: parent INTEGER :: q END TYPE TYPE, extends(parent) :: child INTEGER :: m END TYPE TYPE, extends(parent) :: second INTEGER :: meow END TYPE CONTAINS SUBROUTINE do_something(this, type_num) CLASS(parent), POINTER :: this INTEGER type_num IF (type_num == 0) THEN ALLOCATE (child::this) ELSE IF (type_num == 1) THEN ALLOCATE (second::this) ENDIF END SUBROUTINE END MODULE PROGRAM testpass USE ptr_types CLASS(child), POINTER :: ctype SELECT TYPE(ctype) CLASS is (parent) CALL do_something(ctype, 0) END SELECT WRITE (*,*) ctype%q END PROGRAM however this still fails. in the select statement it complains that parent must extend child. Im sure this is due to restrictions when dealing with the pointer attribute, for type safety, however, im looking for a way to convert a pointer into its parent type for generic allocation. Rather than have to write separate allocation functions for every type and hope they dont collide in an interface or something. hopefully this example will illustrate a little more clearly what im trying to achieve, if you know a better way let me know

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  • Remote mouse pointer not visible in VNC

    - by aef
    I used VNC desktops as a kind of collaboration server, as shared planning and pair programming environment for a long time. Now my latest iteration uses a KVM guest running Fedora 17 "Beefy Miracle", the Cinnamon desktop environment and an X11VNC server. The X11VNC server is automatically started with the desktop environment using the following command: x11vnc -localhost -many -shared -display :0 -bg My problem is that depending on the VNC client, the mouse pointer of the remote system which is shown through VNC is not synchronized to my client. I really need this, so I can see what my partner is doing on the desktop. When using Vinagre 3.2.1 on Ubuntu Oneiric Ocelot (11.10) or Vinagre 2.3.0.3 on Debian Squeeze (6.0) and I don't have my local mouse pointer inside the VNC view, I cannot see the mouse pointer of my remote system, nor its movement. When using TightVNC on Windows 7, I can recognize a mouse pointer trace for very short amounts of time after moving the mouse, but it is not clearly visible. Using UltraVNC on Windows 7 the mouse pointer is clearly visible all the time. With Gnome 2 I never had any problems with remote pointer synchronization, using exactly the same clients. I suspect this could have something to do with Cinnamon's dependency on 3D acceleration. On the other hand, it doesn't change anything to start Cinnamon's fallback environment Cinnamon 2D. Update: Same effect when I use Gnome 3.

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  • How to format a function pointer?

    - by Longpoke
    Is there any way to print a pointer to a function in ANSI C? Of course this means you have to cast the function pointer to void pointer, but it appears that's not possible?? #include <stdio.h> int main() { int (*funcptr)() = main; printf("%p\n", (void* )funcptr); printf("%p\n", (void* )main); return 0; } $ gcc -ansi -pedantic -Wall test.c -o test test.c: In function 'main': test.c:6: warning: ISO C forbids conversion of function pointer to object pointer type test.c:7: warning: ISO C forbids conversion of function pointer to object pointer type $ ./test 0x400518 0x400518 It's "working", but non-standard...

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  • runtime error: invalid memory address or nil pointer dereference

    - by Klink
    I want to learn OpenGL 3.0 with golang. But when i try to compile some code, i get many errors. package main import ( "os" //"errors" "fmt" //gl "github.com/chsc/gogl/gl33" //"github.com/jteeuwen/glfw" "github.com/go-gl/gl" "github.com/go-gl/glfw" "runtime" "time" ) var ( width int = 640 height int = 480 ) var ( points = []float32{0.0, 0.8, -0.8, -0.8, 0.8, -0.8} ) func initScene() { gl.Init() gl.ClearColor(0.0, 0.5, 1.0, 1.0) gl.Enable(gl.CULL_FACE) gl.Viewport(0, 0, 800, 600) } func glfwInitWindowContext() { if err := glfw.Init(); err != nil { fmt.Fprintf(os.Stderr, "glfw_Init: %s\n", err) glfw.Terminate() } glfw.OpenWindowHint(glfw.FsaaSamples, 1) glfw.OpenWindowHint(glfw.WindowNoResize, 1) if err := glfw.OpenWindow(width, height, 0, 0, 0, 0, 32, 0, glfw.Windowed); err != nil { fmt.Fprintf(os.Stderr, "glfw_Window: %s\n", err) glfw.CloseWindow() } glfw.SetSwapInterval(1) glfw.SetWindowTitle("Title") } func drawScene() { for glfw.WindowParam(glfw.Opened) == 1 { gl.Clear(gl.COLOR_BUFFER_BIT) vertexShaderSrc := `#version 120 attribute vec2 coord2d; void main(void) { gl_Position = vec4(coord2d, 0.0, 1.0); }` vertexShader := gl.CreateShader(gl.VERTEX_SHADER) vertexShader.Source(vertexShaderSrc) vertexShader.Compile() fragmentShaderSrc := `#version 120 void main(void) { gl_FragColor[0] = 0.0; gl_FragColor[1] = 0.0; gl_FragColor[2] = 1.0; }` fragmentShader := gl.CreateShader(gl.FRAGMENT_SHADER) fragmentShader.Source(fragmentShaderSrc) fragmentShader.Compile() program := gl.CreateProgram() program.AttachShader(vertexShader) program.AttachShader(fragmentShader) program.Link() attribute_coord2d := program.GetAttribLocation("coord2d") program.Use() //attribute_coord2d.AttribPointer(size, typ, normalized, stride, pointer) attribute_coord2d.EnableArray() attribute_coord2d.AttribPointer(0, 3, false, 0, &(points[0])) //gl.DrawArrays(gl.TRIANGLES, 0, len(points)) gl.DrawArrays(gl.TRIANGLES, 0, 3) glfw.SwapBuffers() inputHandler() time.Sleep(100 * time.Millisecond) } } func inputHandler() { glfw.Enable(glfw.StickyKeys) if glfw.Key(glfw.KeyEsc) == glfw.KeyPress { //gl.DeleteBuffers(2, &uiVBO[0]) glfw.Terminate() } if glfw.Key(glfw.KeyF2) == glfw.KeyPress { glfw.SetWindowTitle("Title2") fmt.Println("Changed to 'Title2'") fmt.Println(len(points)) } if glfw.Key(glfw.KeyF1) == glfw.KeyPress { glfw.SetWindowTitle("Title1") fmt.Println("Changed to 'Title1'") } } func main() { runtime.LockOSThread() glfwInitWindowContext() initScene() drawScene() } And after that: panic: runtime error: invalid memory address or nil pointer dereference [signal 0xb code=0x1 addr=0x0 pc=0x41bc6f74] goroutine 1 [syscall]: github.com/go-gl/gl._Cfunc_glDrawArrays(0x4, 0x7f8500000003) /tmp/go-build463568685/github.com/go-gl/gl/_obj/_cgo_defun.c:610 +0x2f github.com/go-gl/gl.DrawArrays(0x4, 0x3, 0x0, 0x45bd70) /tmp/go-build463568685/github.com/go-gl/gl/_obj/gl.cgo1.go:1922 +0x33 main.drawScene() /home/klink/Dev/Go/gogl/gopher/exper.go:85 +0x1e6 main.main() /home/klink/Dev/Go/gogl/gopher/exper.go:116 +0x27 goroutine 2 [syscall]: created by runtime.main /build/buildd/golang-1/src/pkg/runtime/proc.c:221 exit status 2

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  • mouse pointer doesn't move

    - by Alessandro Cosentino
    From one week ago, I am experiencing this issue with a USB mouse on Kubuntu 12.04: the mouse pointer doesn't move unless I hit a click on the left button. After the click, it moves regularly, but as soon as I stop it, it needs another click to reactivate. The weird thing is that the same mouse behaves normally on my desktop computer, which has the same linux distribution with the same updates. Update: I realized that on my laptop this happens only when the machine runs on battery.

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  • Launcher Disappears, Mouse Pointer Stops Moving

    - by Zachary Rogers
    Quite frequently, when using Ubuntu 12.04 I will have a problem where the launcher disappears and at the same time the mouse cursor will appear to stop moving. However I can actually click on things on other parts of the screen and the pointer will change shape appropriate for what it's actually pointing at. I can left click on things and a menu will appear as normal. I do not have the launcher set to automatically disappear.

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  • LOB Pointer Indexing Proposal

    - by jchang
    My observations are that IO to lob pages (and row overflow pages as well?) is restricted to synchronous IO, which can result in serious problems when these reside on disk drive storage. Even if the storage system is comprised of hundreds of HDDs, the realizable IO performance to lob pages is that of a single disk, with some improvement in parallel execution plans. The reason for this appears to be that each thread must work its way through a page to find the lob pointer information, and then generates...(read more)

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  • Returning a struct pointer

    - by idealistikz
    Suppose I have the following struct and function returning a pointer: typedef struct { int num; void *nums; int size; } Mystruct; Mystruct *mystruct(int num, int size) { .... } I want to define any Mystruct pointer using the above function. Should I declare a Mystruct variable, define the properties of Mystruct, assign a pointer to it, and return the pointer or define the properties of a mystruct property through a pointer immediately?

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  • How does compiler understand the pointer type?

    - by Narek
    How c++ compiler understands the pointer type? As I know pointer has a size equal to WORD of the OS (32 or 64). So does it store dome info in that 32(or 64) bits about type? Just because you can not have a pointer on one type and assign to that pointer another pointer with a different type.

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  • SpriteBatch.end() generating null pointer exception

    - by odaymichael
    I am getting a null pointer exception using libGDX that the debugger points as the SpriteBatch.end() line. I was wondering what would cause this. Here is the offending code block, specifically the batch.end() line: batch.begin(); for (int j = 0; j < 3; j++) for (int i = 0; i < 3; i++) if (zoomgrid[i][j].getPiece().getImage() != null) zoomgrid[i][j].getPiece().getImage().draw(batch); batch.end(); The top of the stack is actually a line that calls lastTexture.bind(); In the flush() method of com.badlogic.gdx.graphics.g2d.SpriteBatch. I appreciate any input, let me know if I haven't included enough information.

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  • Mouse pointer size problem

    - by Rasmus Pedersen
    My mouse cursor is double the normal size. Its only the default pointer that is enlarged. Variations like resize, busy and so on are the correct size. The problem persists even when I change cursor theme. If I move the cursor inside a Firefox window it changes to the correct size. My resolution is 2560x1440, its a single screen setup. Nvidia-settings reports my DPI to be: 108x107. I've tired to force that DPI in the LightDM conf, since I figured it must have something to-do with the DPI calculation. I have tried to change the cursor size through dconf but the problem still remains. I haven't seen this problem before, it arrived after the upgrade from Beta 2 to release version of Ubuntu 11.10. Anybody got any idea what the problem might be, its pretty annoying with the huge cursor.

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  • Pointer initialization doubt

    - by Jestin Joy
    We could initialize a character pointer like this in C. char *c="test"; Where c points to the first character(t). But when I gave code like below. It gives segmentation fault. #include<stdio.h> #include<stdlib.h> main() { int *i; *i=0; printf("%d",*i); } But when I give #include<stdio.h> #include<stdlib.h> main() { int *i; i=(int *)malloc(2); *i=0; printf("%d",*i); } It works( gives output 0). Also when I give malloc(0), It also works( gives output 0). Please tell what is happening

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  • Choppy/unresponsive keyboard and mouse pointer until suspend

    - by Stefan Thyberg
    I had a problem where my mouse and keyboard would be choppy, the mouse pointer would work at 1-2 fps and the keyboard would keep missing letters as I was typing them. Since they were both USB I suspected there was a problem there immediately. Whenever I got this problem I would suspend the computer and start it again and the problem would be gone. The problem started appearing when I plugged the mouse and keyboard directly into the computer rather than the USB hub in the screen. I'm using a Logitech UltraX Flat and a Razer Lachesis, but I'm not sure if that matters.

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  • Choppy/unresponsive keyboard and mouse pointer until suspend

    - by Stefan Thyberg
    I had a problem where my mouse and keyboard would be choppy. The mouse pointer would work at "1-2 fps" and the keyboard would keep missing letters as i was typing them. Since both are USB-Devices, i suspected a problem there immediately, so whenever i got this problem, i would suspend the computer and start it again, for the problem to be gone. The problem started appearing when I plugged the mouse and keyboard directly into the computer rather than the USB-Hub in the screen. I'm using a Logitech UltraX Flat and a Razer Lachesis, on a Dell Latitude E6510.

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  • Take Camera Phone Macro Photos with a Cheap Laser Pointer Lens

    - by Jason Fitzpatrick
    Inside those cheap laser pointers you see in the grocery store checkout line there’s a handy little plastic lens that, when slapped on your phone’s camera, makes it easy to take macro photographs. In this tutorial, they take the lens from a laser point and secure it using tape and a bobby pin. An alternative method to achieve the same end (and with a higher quality lens) is to dismantle a CD/DVD drive to source the lens and use painter’s tape to hold the lens in place–this is the technique I used several years ago, check out the tutorial video here. Laser Pointer Macro Lens [via Apartment Therapy] How to Get Pro Features in Windows Home Versions with Third Party Tools HTG Explains: Is ReadyBoost Worth Using? HTG Explains: What The Windows Event Viewer Is and How You Can Use It

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