Allow float decay epochs arg for training, works out with step lr math

Author: rwightman

train.py

@@ -89,7 +89,7 @@
                     help='number of epochs to train (default: 2)')
 parser.add_argument('--start-epoch', default=None, type=int, metavar='N',
                     help='manual epoch number (useful on restarts)')
-parser.add_argument('--decay-epochs', type=int, default=30, metavar='N',
+parser.add_argument('--decay-epochs', type=float, default=30, metavar='N',
                     help='epoch interval to decay LR')
 parser.add_argument('--warmup-epochs', type=int, default=3, metavar='N',
                     help='epochs to warmup LR, if scheduler supports')