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. (Left-to-right). If (, ) = (, ) AND values increase to AND values switch directions between increasing
and decreasing at least twice AND (, ) = (, ), then go to Step  6.
Step  3. (Right-to-left). 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. (Bottom-to-top). 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. (Top-to-bottom). 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.
Procedure 3: Identifying linear scanpaths.