r1: READ VALUES=p2.X  FILE=input_colvar 
r2: READ VALUES=p3.* FILE=input_colvar
PRINT ARG=r1.*,r2.* STRIDE=1000 FILE=colvar FMT=%8.4f
r3: READ VALUES=p2.X  FILE=input_colvar2 EVERY=2 IGNORE_TIME
PRINT ARG=r3.X FILE=colvar2
