def eval_rmse(pred, truth):
    """
    Evaluate root mean squared error, using sample mean as point estimate.

    :param torch.Tensor pred: Forecasted samples.
    :param torch.Tensor truth: Ground truth.
    :rtype: float
    """
    pred = pred.mean(0)
    error = pred - truth
    return (error * error).mean().cpu().item() ** 0.5