title: Gnu Scientific Library stopped working in Ubuntu 16.04
body: <p>I had GSL (Gnu Scientific library) installed on my Ubuntu 14.04 and it was working fine. I then upgraded to Ubuntu 16.04 and now if I try to compile C++ code using GSL I obtain the error message</p>
  
  <pre><code>g++ -c FILE.cpp
  In file included from FILE.cpp:1:0:
  FILE.h:3:28: fatal error: gsl/gsl_matrix.h: No such file or directory
  compilation terminated.
  Makefile:42: recipe for target 'FILE.o' failed
  make: *** [FILE.o] Error 1
  </code></pre>
  
  <p>How do I fix this issue?</p>