code: private static Class<?> loadJamaMatrixClass() 
              throws ClassNotFoundException {
  
          try {
              Class<?> clazz = Class.forName("Jama.Matrix");
              return clazz;
              
          } catch (ClassNotFoundException cnfe) {
  
              // If we see a CNFE, don't immediately give up.  It's most likely
              // that this class is being invoked from inside a .jar, so see if
              // the user specified where JAMA is manually.
              String jamaProp = System.getProperty("jama.path");
              
              // if not, rethrow since the class does not exist
              if (jamaProp == null)
                  throw cnfe;
  
              File jamaJarFile = new File(jamaProp);            
              try {
                  // Otherwise, try to load the class from the specified .jar file
                  java.net.URLClassLoader classLoader = 
                      new java.net.URLClassLoader(
                          new java.net.URL[] { jamaJarFile.toURI().toURL() });
                  
                  Class<?> clazz = Class.forName("Jama.Matrix", true,
                                                 classLoader);
                  return clazz;
              } catch (Exception e) {
                  // fall through and rethrow original
              }
              
              throw cnfe;
          }
      }
docs: Reflectively loads the JAMA Matrix class.  If the class is not
  immediately loadable from the existing classpath, then this method will
  attempt to use the {@code jama.path} system environment variable to load
  it from an external resource.