Basic Adding - Expression was too complex error (Swift) -

trying add simple numbers together. "expression complex solved in reasonable time..." error on final line. why? surely can't come simpler?

    let year   = calendar.component(.calendarunityear, fromdate: inputgregoriandate)     let month  = calendar.component(.calendarunitmonth, fromdate: inputgregoriandate)       let day    = calendar.component(.calendarunitday, fromdate: inputgregoriandate)      // conversion calulation     let agr = year/100     let bgr = agr/4     let cgr = 2 - agr + bgr     var egr = 0.00     if (month <= 2 ) {         egr = 365.25 * double(year + 4716)     } else {         egr = 365.25 * double(year + 4716);     }     let fgr = 30.6001 * double(month + 1);     let datejulian = double(cgr + day + egr + fgr - 1524.5) 

// conversion calulation let agr = double(year) / 100 let bgr = agr / 4.0 let cgr = 2.0 - agr + bgr var egr = 0.0  // conditional doesn't make sense if (month <= 2 ) {     egr = 365.25 * double(year + 4716) } else {     egr = 365.25 * double(year + 4716) }  let fgr = 30.6001 * double(month + 1) let datejulian = cgr + double(day) + egr + fgr - 1524.5