replaced Double.magnitude (introduced only in Xcode 8.3) with standard abs() function
replaced Double.magnitude (introduced only in Xcode 8.3) with standard abs() function

alex-vasenin/SwiftAA,onekiloparsec/SwiftAA,alex-vasenin/SwiftAA,onekiloparsec/SwiftAA,onekiloparsec/SwiftAA,alex-vasenin/SwiftAA,alex-vasenin/SwiftAA,onekiloparsec/SwiftAA,onekiloparsec/SwiftAA,alex-vasenin/SwiftAA