altered a calculation method per review comments
altered a calculation method per review comments


Former-commit-id: 6dcf0777f879410c6425f1e4912cbc394c6e08dd [formerly 6dcf0777f879410c6425f1e4912cbc394c6e08dd [formerly 1f0b834a287fabd0b03205a419e29eb69e3b6f8b]]
Former-commit-id: 7cbfd22621754f0e911a63fa7a48c2b66877dc77
Former-commit-id: ac99cd31ec084632ec866ece3c0f49158e7f006f
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine