I'm writing program on c++ that needs to generate graphs and calculate some measures.I'm working with Visual Studio 2013 and Igraph C library. At this point I can create graphs from custom info and calculate some metrics like betweennes and closeness centrality, but when i try to calculate eigenvector centrality, the program crash and show me this message:
"Run-Time Check Failure #3 - The variable 'tgetv0' is being used without being initialized."
The tgetv0 variable is used inside of dgetv.c from Igraph source.
Here is my code:
void GraphObject::calcEigen()
{
igraph_arpack_options_t options;
igraph_real_t value;
igraph_vector_t weights;
igraph_vector_init(&weights, igraph_ecount(&cGraph)); //cGraph is already created.
igraph_vector_init(&eigenRes, igraph_vcount(&cGraph)); //All ..Res igraph_vector_t are declarated in header
igraph_vector_init(&betweennesRes, 0);
igraph_vector_init(&closenessRes, 0);
igraph_arpack_options_init(&options);
igraph_betweenness(&cGraph, &betweennesRes, igraph_vss_all(), 0, 0, 1);
igraph_closeness(&cGraph, &closenessRes, igraph_vss_all(), IGRAPH_ALL, 0, 1);
igraph_eigenvector_centrality(&cGraph, &eigenRes, &value, 0, 1, &weights, &options);
}
The closeness and betwenness are correctly calculated an "couted" but crash on eigenvector function.
After lot of research on documentation, internet and the debugger i cant't figure which is the problem, especially when I tryed the example code in the documentation http://igraph.org/c/doc/igraph-Structural.html#igraph_eigenvector_centrality (copy/paste) and makes the same. Is this a library or example issue, I a'm missing something?
When I init the weights vector and then I call igraph_null(&weights), it works but the result of all eigenvalues is 1, and this is incorrect result. What I'm doing wrong?
Let us assume that Visual Studio is right and we indeed have a variable named tgetv0 that is being used uninitialized. I scanned igraph's source code and it looks like there are two places where it could indeed be the case. One of them is in src/lapack/dnaupd.c, the other one is in src/lapack/dsaupd.c. Both of these files were converted from Fortran using f2c so it is hard to tell whether the issue was present in the original Fortran code or whether this was introduced during the conversion. Either way, you can probably fix this easily by looking up the lines where tgetv0 is declared in src/lapack/dnaupd.c and src/lapack/dsaupd.c and initializing it to a value of 0. In my version, the lines to change are line 486 in src/lapack/dnaupd.c and line 482 in src/lapack/dsaupd.c.
Please add a comment to confirm whether the solution works for you or not - if it works, I'll commit a patch to the igraph source tree.
Related
See below for the following code, and below that, the error that follows.
std::string source = "C:\\Users\\cambarchian\\Documents\\tested";
std::string destination = "C:\\Users\\cambarchian\\Documents\\tester";
std::filesystem::path sourcepath = source;
std::filesystem::path destpath = destination;
std::filesystem::copy_options::update_existing;
std::filesystem::copy(sourcepath, destpath);
terminate called after throwing an instance of 'std::filesystem::__cxx11::filesystem_error'
what(): filesystem error: cannot copy: File exists [C:\Users\cambarchian\Documents\tested] [C:\Users\cambarchian\Documents\tester]
Tried to use filesystem::copy, along with trying different paths. No luck with anything. Not too much I can write here as the problem is listed above, could be a simple formatting issue. That being said, it worked on my home computer using visual studio 2022, however using VS Code with gcc 11.2 gives me this issue.
Using:
filesystem::copy_file(oldPath, newPath, filesystem::copy_options::overwrite_existing);
The overloads of std::filesystem::copy are documented. You're using the first overload, but want the second:
void copy(from, to) which is equivalent to [overload 2, below] using copy_options::none
void copy(from, to, options)
Writing the statement std::filesystem::copy_options::update_existing; before calling copy doesn't achieve anything at all, whereas passing the option to the correct overload like
std::filesystem::copy(sourcepath, destpath,
std::filesystem::copy_options::update_existing);
should do what you want.
... it worked on my home computer using visual studio 2022 ...
you don't say whether the destination file existed in that case, which is the first thing you should check.
I put the copy_options within the copy function but it didn't work so I started moving it around, I probably should have mentioned that.
Randomly permuting your code isn't a good way of generating clean examples for others to help with.
In the rare event that hacking away at something does fix it, I strongly recommend pausing to figure out why. When you've hacked away at something and it still doesn't work, by all means leave comments to remind yourself what you tried, but the code itself should still be in a good state.
Still doesn't work when I write std::filesystem::copy(sourcepath, destpath, std::filesystem::copy_options::recursive)
Well, that's a different option, isn't it? Were you randomly permuting which copy_options you selected as well?
Trying recursive and update_existing yields the same issue.
The documentation says
The behavior is undefined if there is more than one option in any of the copy_options option group present in options (even in the copy_file group).
so you shouldn't be setting both anyway. There's no benefit to recursively copying a single file, but there may be a benefit to updating or overwriting one. If the destination already exists. Which, according to your error, it does.
Since you do have an error explicitly saying "File exists", you should certainly look at the "options controlling copy_file() when the file already exists" section of the table here.
Visual Studio 2022 fixed the problem
In R the cumulative distribution function for the binomial distribution is called via an underlying C/C++ function called C_pbinom. I am trying to find the underlying code for this algorithm, so that I can find out what algorithm this function uses to compute the cumulative distribution function. Unfortunately, I have not been successful in finding the underlying code, nor any information on the algorithm that is used.
My question: How do I find the underlying C/C++ code for the function C_pbinom. Alternatively, is there any information source available showing the algorithm used by this function?
What I have done so far: Calling pbinom in R gives the following details:
function (q, size, prob, lower.tail = TRUE, log.p = FALSE)
.Call(C_pbinom, q, size, prob, lower.tail, log.p)
<bytecode: 0x000000000948c5a0>
<environment: namespace:stats>
I have located and opened the underlying NAMESPACE file in the stats library. This file lists various functions, including the pbinom function, but does not give code for the C_pbinom function, nor any pointer to where it can be found. I have also read a related answer on finding source code in R, and an article here on "compiling source codes", but neither has been of sufficient assistance to let me find the code. At this point I have his a dead end.
I went to the Github mirror for the R source code, searched for pbinom, and filtered to C: that got me here. The meat of the function is simply
pbeta(p, x + 1, n - x, !lower_tail, log_p)
This is invoking the incomplete beta function (= CDF of the Beta distribution): it means you need to in turn look up the pbeta function in the code: here, it says that the code is "a wrapper for TOMS708" , which is in src/nmath/toms708.c and described in a little more detail here (google "TOMS 708") ... original code here.
The full reference is here: Didonato and Morris, Jr.,
ACM Transactions on Mathematical Software (TOMS), Volume 18 Issue 3, Sept. 1992, Pages 360-373.
The Point Cloud library comes with an executable pcl_hdl_viewer_simple that I can run (./pcl_hdl_viewer_simple) without any extra arguments to get live data from a Velodyne LIDAR HDL32.
The source code for this program is supposed to be hdl_viewer_simple.cpp. A simplified version of the code is given on this page which cannot be compiled readily and requires a tiny bit of tweaking to make it compile.
My problem is that the executable that I build myself for both the versions are not able to run. I always get the smart pointer error "Assertion px!=0" error. I am not sure if I am not executing the program in the correct way or what. The executable is supposed to be executed like
./hdl_viewer_simple -calibrationFile hdl32calib.xml -pcapFile file.pcap
in case of playing from previously recorded PCAP files or just ./hdl_viewer_simple if wanting to get live data from the real sensor. However, I always get the assertion failed error.
Has anyone been able to run the executables? I do not want to use the ROS drivers
"Assertion px!=0" is occurring because your pointer is not initialized.
Now that being said, you could initialize it inside your routines, in case the pointer is NULL, especially for data input.
in here, you can try updating the line 83 like this :
CloudConstPtr cloud(new Cloud); //initializing your pointer
and hopefully, it will work.
Cheers,
Have you ever run into issue where function in SFML 2 to get availiable modes returns you:
availiableVideoModes [3]({width=3131961357 height=3131961357 bitsPerPixel=3131961357 },{width=3131961357 height=3131961357 bitsPerPixel=3131961357 },{width=3131961357 height=3131961357 bitsPerPixel=3131961357 }) std::vector >
max int values in vector? Interesting is why 3? I tried quick debugging without luck so in parallel I thought to raise question here.
code:
std::vector<sf::VideoMode> availiableVideoModes;
availiableVideoModes = sf::VideoMode::getFullscreenModes();
interesting is that
desktopVideoMode = sf::VideoMode::getDesktopMode();
returns correct value.
The issue was in libraries link, I have linked 32bits one instead of 64bits.
I do some image processing work in C++. For this i use CImg.h library which i feel is good for my work.
Here is small piece of code written by me which just reads an image and displays it.
#include "../CImg.h"
#include "iostream"
using namespace std;
using namespace cimg_library;
int main(int argc,char**argv)
{
CImg<unsigned char> img(argv[1]);
img.display();
return 0;
}
When i give lena.pgm as input this code it displays the image. Where as if i give some other image, for example ddnl.pgm which i present in the same directory i get "Segmentation Fault".
When i ran the code using gdb i get the output as follows:
Program received signal SIGSEGV, Segmentation fault.
0x009823a3 in strlen () from /lib/libc.so.6
Missing separate debuginfos, use: debuginfo-install glibc-2.9-2.i686 libX11-1.1.4-5.fc10.i386 libXau-1.0.4-1.fc10.i386 libXdmcp-1.0.2-6.fc10.i386 libgcc-4.3.2-7.i386 libstdc++-4.3.2-7.i386 libxcb-1.1.91-5.fc10.i386
Can some one please tell me what the problem is? and how to solve it.
Thank you all
Segfault comes when you are trying to access memrory which you are not allowed to access.
So please check that out in the code.
The code itself looks just fine. I can suggest some ways to go ahead with debugging -
Try removing the display() call. Does the problem still occur? (I'd assume it does).
Try finding out where in the CImg code is the strlen() that causes the segmentation fault (by using a debugger). This may give additional hints.
If it is in the PGM file processing, maybe the provided PGM file is invalid in some way, and the library doesn't do error detection - try opening it in some other viewer, and saving it again (as PGM). If the new one works, comparing the two may reveal something.
Once you have more information, more can be said.
EDIT -
Looking at the extra information you provided, and consulting the code itself, it appears that CImg is failing when trying to check what kind of file you are opening.
The relevant line of code is -
if (!cimg::strcmp(ftype,"pnm")) load_pnm(filename);
This is the first time 'ftype' is used, which brings me to the conclusion that it has an invalid value.
'ftype' is being given a value just a few lines above -
const char *const ftype = cimg::file_type(0,filename);
The file_type() function itself tries to guess what file to open based on its header, probably because opening it based on the extension - failed. There is only one sane way for it to return an invalid value, which would later cause strcmp() to fail - when it fails to identify the file as anything it is familiar with, it returns NULL (0, actually).
So, I reiterate my suggestion that you try to verify that this is indeed a valid file. I can't point you at any tools that are capable of opening/saving PGM files, but I'm guessing a simple Google search would help. Try to open the file and re-save it as PGM.
Another "fun to track down" cause of segmentation faults is compilier mismatches between libraries - this is especially prevalent when using C++ libraries.
Things to check are:
Are you compiling with the same compiler as was used to compile the CImg library?
Are you using the same compiler flags?
Were there any defines that were set when compiling the library that you're not setting now?
Each of these has bitten me in subtle ways before.