def ExcessPowerPreFunc(sngl_burst_table):
    """
	For speed, convert peak times to floats relative to epoch.
	"""
    if not len(sngl_burst_table):
        return
    offset = sngl_burst_table[0].peak
    for row in sngl_burst_table:
        row.peak_time = float(row.peak - offset)
    return offset
