INPUT Fundamental IGS  OUTPUT Linear scanpath  Let (, ) be the coordinates of an eye fixated target where is an indicator for sequential eye fixations.  Let , , , and .  Step 1. When an eye fixated target is an extreme point on the or axis on the screen, let it be (, ).  Step 2. (Lefttoright). If (, ) = (, ) AND values increase to AND values switch directions between increasing  and decreasing at least twice AND (, ) = (, ), then go to Step 6.  Step 3. (Righttoleft). Else if (, ) = (, Y) AND values decrease to AND values switch directions between  increasing and decreasing at least twice AND (, ) = (, ), then go to Step 6.  Step 4. (Bottomtotop). Else if (, ) = (, ) AND values increase to AND values switch directions between  increasing and decreasing at least twice AND (, ) = (, ), then go to Step 6.  Step 5. (Toptobottom). Else if (, ) = (, ) AND values decrease to AND values switch directions between  increasing and decreasing at least twice AND (, ) = (, ), then go to Step 6.  Step 6. If , then the pattern is labeled linear.  Note: Identification of linear scans with diagonal movements are evaluated by repeating the steps after rotating the display by 45  degrees. 
