小行星

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('config', metavar='CFG',
                    help='path to configuration')
parser.add_argument('-t', '--threads', type=int, default=4,
                    help="how many GPUs are avaliable on this machine")
parser.add_argument('-num', '--nums_epoch', default=200, type=int,
                    help='nums of epochs')
parser.add_argument('-save_dir', '--save_dir', default="tmp", type=str,
                    help='save_dir')
parser.add_argument('-gpus', '--gpus', nargs='+', type=int,
                    help='--gpus 1234 2345 3456 4567 ')

import torch
a = torch.tensor(0.0)
b = torch.tensor(0.0)

a.requires_grad = True
b.requires_grad = True

cosa = torch.cos(a)
cosb = torch.cos(b)

y1 = cosa + cosb
y2 = torch.tensor([
    cosa, cosb
])

y2.sum().backward()  # RuntimeError: element 0 of tensors does not require grad and does not have a grad_fn

print("a has grad ", a.requires_grad)
print("a grad", a.grad)

y2 = torch.cat([
    cosa, cosb
], dim=0)

out[out > 0] = 1
out[out <= 0] = -1