So you tried to make a link to /usr/lib/x86_64-linux-gnu/libgsl.so
but that actual file does not exist.
Try pointing the link at the existing so.19.0.0 file:
sudo rm /usr/lib/libgsl.so.0
sudo ln -s /usr/lib/x86_64-linux-gnu/libgsl.so.19.0.0 /usr/lib/libgsl.so.0
- rick
