Background
I am trying to find the eigenvalues of a complex matrix by using zgeev routine in LAPACK library. As far as I understand, LAPACK is written for FORTRAN and hence to use it with a C (or C++) program one has to make several modifications such as transforming the matrix and appending an underscore in the routine-name (REFERENCE:http://www.physics.orst.edu/~rubin/nacphy/lapack/codes/eigen-c.html)
Problem
To link LAPACK library to a C++ program (http://www.physics.orst.edu/~rubin/nacphy/lapack/codes/eigen-c.html)
and
compile it with g++ on cygwin on my windows 7 laptop, I am using the following command:
$ g++ eigen_complex.cpp -L G:\cygwin_root_dir\lib -lliblapack.a -llibblas.a
and getiing the following result:
eigen_complex.cpp: In function `int main()':
eigen_complex.cpp:41: error: `zgeev_' undeclared (first use this function)
eigen_complex.cpp:41: error: (Each undeclared identifier is reported only once for each function it appears in.)
I don't understand what is causing this error. Changing the name of the library from liblapack to lapack or to anything (say "lapa") does not make any difference to the error.
The following compiling commands return the same result as above
g++ eigen_complex.cpp -L G:\cygwin_root_dir\lib -llapack.a -lblas.a
g++ eigen_complex.cpp -L G:\cygwin_root_dir\lib -llapack -lblas
g++ eigen_complex.cpp -L G:\cygwin_root_dir\lib -lliblapack -llibblas
g++ eigen_complex.cpp -lliblapack -llibblas
and
g++ eigen_complex.cpp -lliblapack -lxyz
also.
I believe there is no library with name xyz and the compiler is not giving any warning about it.
Any help will be greatly appreciated.
Hopefully adding this prototype in a header somewhere in your project should resolve it:
extern "C" void zgeev_(char*, char*,int*,double *, int*, struct complex [], struct complex [1][1], int*, struct complex [1][1], int*, struct complex [], int*, struct complex [], int*);
Related
I am new to g++ and lapack, and attempting to use them. I encountered a problem when I tried to compile the following naive code
#include <lapackpp.h>
int main()
{
LaGenMatDouble A;
return 0;
}
If I run the command
$g++ -L/usr/local/lib -llapackpp test2.cpp
where test2.cpp is the name of the cpp file, the terminal would give an error:
test2.cpp:1:22: fatal error: lapackpp.h: No such file or directory
But if I run the command:
$g++ -I/usr/local/include/lapackpp -L/usr/local/lib -llapackpp test2.cpp
the terminal would give an error:
/tmp/ccUi11DG.o: In function `main':
test2.cpp:(.text+0x12): undefined reference to `LaGenMatDouble::LaGenMatDouble()'
test2.cpp:(.text+0x23): undefined reference to `LaGenMatDouble::~LaGenMatDouble()'
collect2: ld returned 1 exit status
BTW, if I run the command
$pkg-config lapackpp --libs
the result is
-L/usr/local/lib -llapackpp
Could you please help me solve this? Thanks in advance!
Lapack requires fortran libraries, so that's where the -lgfortran comes from. Moreover, it appears the exact way to provide that library for the compiler depends on the Linux distriburion. From the documentation:
Requirements
This package requires the packages "blas", "lapack" (without the "++"), and a Fortran compiler. On most Linuxes these are available as pre-compiled binaries under the name "blas" and "lapack". For SuSE 10.x, the Fortran compiler is available as package "gfortran". For SuSE 9.x, the Fortran compiler is available as package "gcc-g77".
Not sure why pkg-config lapackpp --libs does not list -lgfortran
The -I/usr/local/include/lapackpp specifes the lapackpp-related header files. Without it the compiler cannot find lapackpp.h when you try to include it (#include <lapackpp.h>) -- see the compiler error in your question
I finally solved the problem but would still wonder why it has to be so.
The only command that can link cpp file to lapackpp library is:
g++ foo.cpp -o foo -lgfortran -llapackpp -I/usr/local/include/lapackpp
It would not work without -lgfortran, or with -I/usr/local/include/lapackpp replaced by -L/usr/local/lib.
Does anyone have an answer?
I'm learning Objective-C language. Since I don't have a Mac, I'm compiling and running my code within Ubuntu 11.04 platform.
Until now, I was using gcc to compile. I've installed GNUStep and all was working. But then I started to try some Objective-C 2.0 features, like #property and #synthesize, that gcc does not allow.
So I tried to compile the code with Clang, but it seems that it is not correctly linking my code with the GNUStep libraries, not even with a simple Hello world program.
For example, if I compile the following code:
#import <Foundation/Foundation.h>
int main(void) {
NSLog(#"Hello world!");
return 0;
}
The output of the compiler is:
/tmp/cc-dHZIp1.o: In function `main':
test.m:(.text+0x1f): undefined reference to `NSLog'
/tmp/cc-dHZIp1.o: In function `.objc_load_function':
test.m:(.text+0x3c): undefined reference to `__objc_exec_class'
collect2: ld returned 1 exit status
clang: error: linker (via gcc) command failed with exit code 1 (use -v to see invocation)
The command I'm using to compile is
clang -I /usr/include/GNUstep/ test.m -o test
with the -I directive to include the GNUStep libraries (otherwise, Clang is not able to find Foundation.h).
I've googled my problem, and visited both GNUStep and Clang web pages, but I haven't found a solution to it. So any help will be appreciated.
Thanks!
The problem was that the library gnustep-base was not being used by the linker. So the solution to this was using the option -Xlinker, that sends arguments to the linker used by clang:
clang -I /usr/include/GNUstep/ -Xlinker -lgnustep-base test.m -o test
The statement "-X linker -lgnustep-base" made the magic. However, I had problems with this command related to the class that represents a string in Objective-C:
./test: Uncaught exception NSInvalidArgumentException, reason: GSFFIInvocation:
Class 'NXConstantString'(instance) does not respond to forwardInvocation: for
'hasSuffix:'
I could solve it adding the argument "-fconstant-string-class=NSConstantString":
clang -I /usr/include/GNUstep/ -fconstant-string-class=NSConstantString \
-Xlinker -lgnustep-base test.m -o test
In addition, I've tried with some Objective-C 2.0 pieces of code and it seems to work.
Thank you for the help!
You can try gcc compiler:
First of all install GNU Objective-C Runtime: sudo apt-get install gobjc
then compile: gcc -o hello hello.m -Wall -lobjc
You are not able to use ObjC 2.0 features because you're missing a ObjC-runtime supporting those. GCC's runtime is old and outdated, it doesn't support ObjC 2.0. Clang/LLVM doesn't have a acompanied runtime, you need to install the ObjC2-runtime from GNUstep (which can be found here: https://github.com/gnustep/libobjc2 ) and reinstall GNUstep using this runtime.
Here are some bash scripts for different Ubuntu versions, that do everything for you:
http://wiki.gnustep.org/index.php/GNUstep_under_Ubuntu_Linux
And please don't try to reinvent GNUstep make, instead, use it:
http://www.gnustep.org/resources/documentation/Developer/Make/Manual/gnustep-make_1.html
If you really don't think so, here is some excerpt from there:
1.2 Structure of a Makefile
Here is an example makefile (named GNUmakefile to emphasis the fact that it relies on special features of the GNU make program).
#
# An example GNUmakefile
#
# Include the common variables defined by the Makefile Package
include $(GNUSTEP_MAKEFILES)/common.make
# Build a simple Objective-C program
TOOL_NAME = simple
# The Objective-C files to compile
simple_OBJC_FILES = simple.m
-include GNUmakefile.preamble
# Include in the rules for making GNUstep command-line programs
include $(GNUSTEP_MAKEFILES)/tool.make
-include GNUmakefile.postamble
This is all that is necessary to define the project.
In your case replace all occurrences of simple with test and you're done
1.3 Running Make
Normally to compile a package which uses the Makefile Package it is purely a matter of typing make from the top-level directory of the package, and the package is compiled without any additional interaction.
I was trying to compile a OpenCV's VideoCapture example. When I compile it, I get the following output:
gpp test.c
Info: resolving vtable for cv::VideoCapture by linking to __imp___ZTVN2cv12VideoCaptureE (auto-import)
c:/programs/mingw/bin/../lib/gcc/mingw32/4.5.0/../../../../mingw32/bin/ld.exe: warning: auto-importing has
enable-auto-import specified on the command line.
This should work unless it involves constant data structures referencing symbols from auto-imported DLLs.
(Btw, gpp is an alias to g++ -lhighgui -lcv -lcxcore)
So, I tried to compile with "gpp --enable-auto-import", but g++ didn't recognize this option. So, I tried to compile like this:
gpp -c test.c
ld test.o
And I've got the same error AND many other errors about STL functions, indicating it didn't link with STL:
undefined reference to std::cout
...
And, finally, when I compiled like this:
gpp -c test.c
ld --enable-auto-import test.o
This time, I've only got the STL errors. The VideoCapture error is gone! So I guess I solved this problem. The only thing is: how do I make ld link my program with STL libraries??????
Thanks in advance
The correct solution is build with
g++ test.c -lhighgui -lcv -lcxcore -Wl,--enable-auto-import
Unlike your 'gpp' alias, this puts libraries after objects which reference them (important when linking with archive libraries), and also properly passes --enable-auto-import flag to the linker.
Your current "fix" only works "by accident".
Using: windows xp, g++ 3.4.4 with cygwin and g++ 3.4.5 with mingw.
I'm compiling a simple unit test class with cppunit.
When I link using g++ 3.4.5 I get a lot of linking errors. When I link with g++ 3.4.4 I don't get any errors and the exe links fine and runs.
I can't seem to trace down the errors, so any thoughts?
Thanks.
EDIT: linking errors: Unreferenced function errors. Like:
SimpleTest.cpp:(.text+0x313): undefined reference to `CppUnit::Message::Message(std::string const&, std::string const&)'
EDIT: cmd line:
g++ -I g:\projects\thirdparty\cppunit-1.12.1\include -L g:\projects\thirdparty\cppunit-1.12.1\lib -l cppunitd -o main.exe main.cpp SimpleTest.cpp
Update: Same code in Visual Studio: No error, unit test runs as expected.
Your problem is likely incorrect link line. The order of sources/object files and libraries on the link line matters. Correct link line:
g++ -I g:\projects\thirdparty\cppunit-1.12.1\include \
-L g:\projects\thirdparty\cppunit-1.12.1\lib \
-o main.exe main.cpp SimpleTest.cpp -lcppunitd
As g++ matures, I'm on 4.2.3, it's type checking has gotten more pedantic and for that matter better. With the little information I'd say it's likely that you should look closely at your calls to these methods. I suspect that the types are not quite right. 3.4.4 doesn't catch it, 3.4.5 does.
....JW
One thing you could perhaps try is to compile with g++ 3.4.5 and/or 3.4.4 on Linux. If the result then is the same, then it is clearly a property of gcc. Otherwise it more sounds like a mingw issue.
Is it possible to build objective c code correctly with GCC under cygwin.
I have the following application that should work on a Mac environment, but can't get the most basic stuff to work with gcc. Are there more libraries I need to have.
#import "HelloWorldApp.h"
int main(int argc, char *argv[]) {
return 0;
} // End of the //
#interface Car
{
int test;
}
//The registration is a read-only field, set by copy
#property int (readonly, copy) test;
//the driver is a weak reference (no retain), and can be modified
//#property Person* (assign) driver;
#end
CC=gcc
CXX=gcc-g++
LD=$(CC)
CFLAGS=
LDFLAGS=-lobjc
all: HelloWorld
HelloWorld: HelloWorld.o
$(LD) $(LDFLAGS) -o $# $^
%.o: %.m
$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $#
clean:
rm -rvf *.o HelloWorld HelloWorld.exe
Error:
gcc -c HelloWorld.m -o HelloWorld.o
In file included from HelloWorld.m:6:
HelloWorldApp.h:19: error: stray '#' in program
HelloWorldApp.h:19: error: parse error before "int"
make: *** [HelloWorld.o] Error 1
I think it's because you're using Objective-C 2.0, which is a private extension that Apple developed and that they did not contribute back to the "standard", FSF GCC. Thus, your mingw compiler (which is not based on Apple's, but on the FSF's) does not understand new syntax like properties.
# Malaxeur - you hit the nail right on the head. I've just been bashing about with ObjC on a PC and had that exact problem - my path was pointing to a v3.x gcc compiler. I switched to the 4.x version and voila!
It's also worth noting that the "stray '#'" error also pops up if you spell 'implementation' wrong, which is a little misleading.
Anyway, thanks for the help.
Have you tried running the gcc commands directly from command line rather than via makefile?
Found this reference:
Taken directly from http://www.cs.indiana.edu/classes/c304/ObjCompile.html
Compiling Objective-C
Objective-C code can be compiled using the GNU C compiler gcc. Objective-C interface files usually marked by the extension .h as in List.h. Implementation files are usually marked by the extension .m as in List.m. The implementation file should #import its corresponding interface file. Your main program should also #import the interface files of all of the classes it uses.
Usually, you will want to compile the files which implement your classes separately. For instance, to compile List.m, use the following command:
gcc -c -Wno-import List.m
The -c switch tells the compiler to produce an object file, List.o, which can then later be linked into your program. Do this for each of your implementation files, and your main program.
The -Wno-import switch tells the compiler not to give a warning if you have a #import statement in your code. For some reason, Richard Stallman (the GNU Project founder) doesn't like the #import construction.
When you are ready to compile your program, you can link all of the implementations of your classes using gcc again. For example, to compile the files List.o, and main.o you could use the following command:
gcc -o prog -Wno-import List.o main.o -lobjc
The -o prog tells gcc to create an executable program with the name prog (if you do not specify this, it will default to a.out.
Note that when linking Objective-C with gcc, you need to specify the Objective-C library by using the -lobjc switch. If gcc reports an error, contact your system administrator to make sure that the Objective-C library and header files (objc/Object.h) were installed when gcc was built.