[Lemon-user] strongly connected components

[Alpár Jüttner]

On Sun, 2010-09-19 at 21:02 -0700, Mark W Redekopp wrote:
> Thanks, that worked.  However, I have two more related questions to
> your eps saving method: 
> 
> 1.) 
> I tried to compile the graph_to_eps_demo.cc available from your link. 
> 
> http://lemon.cs.elte.hu/pub/doc/1.1.1/a00302.html

Note that version 1.1.1 is not the latest one. Though it is still
supported, version 1.2 is recommended for its new features.
> 
> When I compile (using g++ 3.4.4 on cygwin) I get the following
> errors: 
> 
>  g++ -o lemon_test_eps -I /home/user/lemon-1.2
> -L /home/user/lemon-1.2/libemon.la lemon_test_eps.cpp 

The option -L is used to add directories to the library search path.
Thus you should use it together with option -l. Alternatively, you can
directly give the .a file (not the .la one) to the compiler without any
option.

Finally, you must place the libraries _after_ the source code.

Therefore

* if /home/user/lemon-1.2 in your example is the installation prefix,
then the compilation command is either

g++ -o lemon_test_eps -I /home/user/lemon-1.2
-L /home/user/lemon-1.2/libs lemon_test_eps.cpp -lemon

or

g++ -o lemon_test_eps -I /home/user/lemon-1.2
lemon_test_eps.cpp /home/user/lemon-1.2/libs/libemon.a


* if /home/user/lemon-1.2 is the location of the source code and you
used autotool to build lemon, then the compilation command is either

g++ -o lemon_test_eps -I /home/user/lemon-1.2
-L /home/user/lemon-1.2/lemon/.libs lemon_test_eps.cpp -lemon

or

g++ -o lemon_test_eps -I /home/user/lemon-1.2
lemon_test_eps.cpp /home/user/lemon-1.2/lemon/.libs/libemon.a

> /tmp/ccH27lgD.o:lemon_test_eps.cpp:(.text
> $_ZN5lemon9distantBWERKNS_5ColorE[lemon::distantBW(lemon::Color
> const&)]+0x67): undefined reference to `lemon::WHITE' 
> [...]
> /tmp/ccH27lgD.o:lemon_test_eps.cpp:(.text
> $_ZN5lemon23DefaultGraphToEpsTraitsINS_11ListDigraphEEC1ERKS1_RSob[lemon::DefaultGraphToEpsTraits<lemon::ListDigraph>::DefaultGraphToEpsTraits(lemon::ListDigraph const&, std::basic_ostream<char, std::char_traits<char> >&, bool)]+0x259): undefined reference to `lemon::BLACK' 
> collect2: ld returned 1 exit status 
> 
> Any ideas where those constants are defined or what I'm doing wrong. 

The reason for the error is that the lemon lib was not properly added.
See above.

> 2.) I wanted the above eps output capability for some other code I
> have.  In that code I have an enum type: 
> 
> enum inst_type_enum {GATE,PI,PO,DFF,BBOX_IN, BBOX_OUT}; 
> 
> As soon as I include the file: 
> 
> #include <lemon/graph_to_eps.h> 
> 
> I start to get errors that my PI enumeration is no longer defined.
> (see below) 
> 
> trust_wrap.cxx: In function `void init_trust()': 
> trust_wrap.cxx:14228: error: `PI' undeclared (first use this
> function) 
> trust_wrap.cxx:14228: error: (Each undeclared identifier is reported
> only once for each function it appears in.) 
> 
> Before when I didn't include <lemon/graph_to_eps.h> (and even when I
> comment it out) I get no errors.  I'm not even trying to call any eps
> functions.  Just including the header file.  I wonder if it includes
> some other file that defines PI or changes something.  Can you offer
> any insight why my 'PI' constant/enum would be altered or 'hidden' by
> include the graph_to_eps file?

Lemon defines a constant PI (for 3.141...), but it is inside the lemon
namespace (lemon::PI) therefore should not cause problem. Could you send
a small example that shows the symptoms?

Regards,
Alpar