set title '2-D Interpolation Error Data, Order 4'
plot 'rms.out' u 1:4 t 'Resolution 1' w lp, \
'' u 1:8 t 'Resolution 2' w lp, \
'' u 1:12 t 'Resolution 3' w lp, \
'' u 1:16 t 'Resolution 4' w lp;