If @{cumulative} is false it will return:\t@{y} * exp (-@{y}*@{x}),otherwise it will return\t1 - exp (-@{y}*@{x}).
Baldin eta @{metatua} faltsua bada, hau ematen du:\t@{y} * exp (-@{y}*@{x}). Bestela hau ematen du:\t1 - exp (-@{y}*@{x}).