import torch


def rmse(hat_y, y):
    """RMSE

    Args:
        hat_y: 预测值
        y: 真实值
    
    Return:
        ('rmse', rmse): 评价指标名称，评价结果
    """
    rmse = torch.sqrt(torch.mean(torch.pow(y - hat_y, 2)))
    return 'rmse', rmse