def mpi_statistics_scalar(x, with_min_and_max=False):
    """
    Get mean/std and optional min/max of scalar x across MPI processes.

    Args:
        x: An array containing samples of the scalar to produce statistics
            for.

        with_min_and_max (bool): If true, return min and max of x in 
            addition to mean and std.
    """
    x = np.array(x, dtype=np.float32)
    global_sum, global_n = mpi_sum([np.sum(x), len(x)])
    mean = global_sum / global_n

    global_sum_sq = mpi_sum(np.sum((x - mean)**2))
    std = np.sqrt(global_sum_sq / global_n)  # compute global std

    if with_min_and_max:
        global_min = mpi_op(np.min(x) if len(x) > 0 else np.inf, op=MPI.MIN)
        global_max = mpi_op(np.max(x) if len(x) > 0 else -np.inf, op=MPI.MAX)
        return mean, std, global_min, global_max
    return mean, std

    Get mean/std and optional min/max of scalar x across MPI processes.

    Args:
        x: An array containing samples of the scalar to produce statistics
            for.

        with_min_and_max (bool): If true, return min and max of x in 
            addition to mean and std.
    
spinup/utils/mpi_tools.py