This function calculates GAP Momentum, a measure of momentum based on the gaps between opening and closing prices over several periods.
Gaps are calculated for defined periods (here, by default, 14 periods). It determines :
UpGaps: the sum of positive gaps, i.e. openings that are higher than the previous period's close.
DnGaps: the sum of negative gaps, i.e. openings below the previous period's close.
It then calculates the GAP Momentum as the ratio between the sum of the up gaps and the sum of the down gaps, multiplied by 100. If the total of the down gaps is zero, the ratio takes a default value of 1 to avoid division by zero.