title: What does undefined symbols for architecture x86_64 mean?
body: <p>I am trying to build eigen on my Mac Air with Lion. I downloaded eigen3 (from <a href="http://eigen.tuxfamily.org/index.php?title=Main_Page" rel="nofollow">http://eigen.tuxfamily.org/index.php?title=Main_Page</a>) and have successfully run <code>make install</code>. However, when I try to run <code>make check</code>, I get the following error.</p>
  
  <pre><code>[  1%] Built target sparse_extra_2
  Linking CXX executable openglsupport
  ld: warning: ignoring file /System/Library/Frameworks//GLEW.framework/GLEW,
              missing required architecture x86_64 in file
  Undefined symbols for architecture x86_64:
    "_glewExperimental", referenced from:
        test_openglsupport() in openglsupport.cpp.o
    "_glewInit", referenced from:
        test_openglsupport() in openglsupport.cpp.o
    "_glBegin", referenced from:
        test_openglsupport() in openglsupport.cpp.o
  </code></pre>
  
  <p>I feel that this issue has to do with glew. I am now trying to install different versions of glew, but that doesn't seem to do anything.</p>
  
  <p>Any advice on how to resolve the error? What does undefined symbols for architecture x86_64 mean anyway?</p>