Pressing the button (28-4) displays the Filter popup window (Figure 29) for interactive filtering of the current time course. To filter a time course, an algorithm consisting of a sequence of equations must be specified in the list (29-1). The first item in the list is always the current time course. Its designation ``S0'' stands for Signal at index 0. Each equation is composed of a resultant signal (i.e. time course), an operation and a set of operands. There are 12 operations available as follows:
After an choice (29-3) is selected, the required operand fields are displayed. For example, for the ``Add'' operation, two source signals are required and thus the (29-4) and (29-5) fields are displayed. After the operation and operands have been specified, the button (29-2) inserts the filtering equation into the algorithm list. Pressing the button (29-9) will remove the item in the algorithm list. When any item in the algorithm list is selected, the resultant signal is displayed back in the Qwik plot window (28-1). The (29-6) and buttons (29-8) can be used to store and retrieve the algorithm to/from a file. The button (29-7) will perform the filter algorithm on the time courses of every voxel in the entire stim volume.
Figure 29: Time Course filter window.