Re: [igraph] community_leading_eigenvector in cpp

[Tamás Nepusz]

Hi,

That's strange because you are not supposed to hit the branch that produces 
this error message if the "start" argument that you pass to 
igraph_community_leading_eigenvector is zero (which is the case here). There is 
a slight possibility that some accidental memory access error somewhere else in 
the code overwrites the value of the "start" argument; can you run your 
executable through Valgrind to see if there are any uninitialized variables or 
invalid reads/writes that could explain this?

All the best,
--  
T.

-----Original Message-----
From:address@hidden <address@hidden>
Reply: Help for igraph users <address@hidden>>
Date: 28 August 2014 at 12:11:31
To:address@hidden <address@hidden>>
Subject:  [igraph] community_leading_eigenvector in cpp

> Hi,
>  
> I am trying to use the function "community_leading_eigenvector()", but I've 
> got the  
> following error:
>  
> # Error:
> Error at community.c:1349 :Wrong length for vector of predefined memberships, 
> Invalid  
> value
>  
> # Information:
> address@hidden:~$ lsb_release -a
> No LSB modules are available.
> Distributor ID: Ubuntu
> Description: Ubuntu 14.04.1 LTS
> Release: 14.04
> Codename: trusty
>  
>  
> $ g++ -v
> Using built-in specs.
> COLLECT_GCC=g++
> COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
> Target: x86_64-linux-gnu
> Configured with: ../src/configure -v --with-pkgversion='Ubuntu 
> 4.8.2-19ubuntu1'  
> --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs 
> --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++  
> --prefix=/usr --program-suffix=-4.8 --enable-shared --enable-linker-build-id  
> --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix 
> --with-gxx-include-dir=/usr/include/c++/4.8  
> --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu 
> --enable-libstdcxx-debug  
> --enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap  
> --enable-plugin --with-system-zlib --disable-browser-plugin 
> --enable-java-awt=gtk  
> --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre 
>  
> --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64  
> --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64 
> --with-arch-directory=amd64  
> --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc 
> --enable-multiarch  
> --disable-werror --with-arch-32=i686 --with-abi=m64 
> --with-multilib-list=m32,m64,mx32  
> --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu 
> --host=x86_64-linux-gnu  
> --target=x86_64-linux-gnu
> Thread model: posix
> gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1)
>  
>  
> g++ leadingeigenvector_test.cpp -I/usr/local/include/igraph/ -ligraph -o 
> leadingeigenvector-zhao  
>  
>  
> # Extract of the code
> …
> f = fopen (inputFilename, "r");
> igraph_read_graph_edgelist(&g, f, 0, IGRAPH_UNDIRECTED);
> fclose(f);
>  
> igraph_simplify(&g, 1, 1, 0);
>  
> igraph_matrix_init(&merges, 0, 0);
> igraph_vector_init(&membership, 0);
> igraph_arpack_options_init(&options);
>  
>  
> clock_t start=clock();
> igraph_community_leading_eigenvector(&g, 0, &merges, &membership, 
> igraph_vcount(&g),  
> &options, &modularity, 0, 0, 0, 0, 0, 0);
> clock_t end=clock();
> …
>  
> # While The same code works on MacOS-X (10.9.4)
> * igraph 0.7.1 installed with Homebrew
> * g++ 4.8
>  
> Does anyone know the reason why there is an error message?
>  
> Best regards,
> Zhao
>  
>  
>  
>  
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