Given time in days, current weight and weight to lose, create a calendar with daily target weights

weight.rb

t0 = Time.local(2012, 12, 19)
time_in_days = 180
cur_w = 90.7
w_delta = 6*2.0
DAY = 86400

target_date = t0 + time_in_days*DAY
target_weight = cur_w - w_delta

daily_loss = w_delta / time_in_days

d = t0
w = cur_w

def year_month(d)
  d.strftime('-=-= %02m/%Y =-=-')
end

def adjusted_wday(d)
  d.wday == 0 ? 6 : d.wday - 1
end

def last_day?(d)
  d.month != (d + DAY).month
end

epsilon = 0.01
while d < target_date
  if d.day == 1 || d == t0
    puts
    puts
    puts year_month(d)
    print ' '*9*adjusted_wday(d)
  end

  w -= daily_loss
  fmt = (w.to_i - w.round(1)).abs <= epsilon ? '%4d' : '%.1f'
  ds, ws = [d.strftime('%-2d'), fmt % w]

  out = ["%3s %4s" % [ds, ws]]
  out << (!d.sunday? || last_day?(d) ? " " : "\n")

  print out.join

  d += DAY
end