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   "source": [
    "# Logging\n",
    "\n",
    "The Python interface for Fulqrum has verbose logging functionality built in.  Here we show an example of logging inside the Jupyter notebook from which this docuement is generated."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "2cb548ff-572f-48ff-866e-6fdb496c06f4",
   "metadata": {},
   "outputs": [],
   "source": [
    "import fulqrum as fq"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "32711ed5-d447-4df4-b686-c0151b5dc8b7",
   "metadata": {},
   "source": [
    "## Formatting the logger\n",
    "\n",
    "Here we show how to format the logger for useful output.  Importantly, when using Jupyter notebooks we need to include `force=True` in the config in order to have the logs show up in the cell output"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "c0d613c5-e7b9-42ef-8a40-c166b014677b",
   "metadata": {},
   "outputs": [],
   "source": [
    "import logging\n",
    "\n",
    "logging.basicConfig(\n",
    "    level=logging.INFO,\n",
    "    force=True,\n",
    "    format=\"%(asctime)s - %(levelname)s - %(name)s - %(message)s\",\n",
    ")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "df505263-a762-46f1-8ab0-65cacdfed18e",
   "metadata": {},
   "source": [
    "## Small example\n",
    "\n",
    "Here we load a molecule, transform it, build a subspace, and finally put them all together in a `SubspaceHamiltonian`.  Having set the logging config above, the ouput from each logger entry will be displayed in the cell output."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "id": "46c3b7e9-2bb9-459a-9be2-fd892e321003",
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "2026-08-19 06:59:27,767 - INFO - fulqrum.core.fermi_operator - Extended JW time: 0.758 ms\n",
      "2026-08-19 06:59:27,768 - INFO - fulqrum.core.subspace - Initializing Subspace\n",
      "2026-08-19 06:59:27,769 - INFO - fulqrum.core.subspace - Full subspace bit-strings\n",
      "2026-08-19 06:59:27,769 - INFO - fulqrum.core.subspace - Subspace size: 4096\n",
      "2026-08-19 06:59:27,769 - INFO - fulqrum.core.subspace - Number of bits: 12\n",
      "2026-08-19 06:59:27,769 - INFO - fulqrum.core.subspace - Using all bitset blocks: True\n",
      "2026-08-19 06:59:27,770 - INFO - fulqrum.core.subspace - Reserve multiplier: 2\n",
      "2026-08-19 06:59:27,770 - INFO - fulqrum.core.subspace - Subspace total init time: 1.587 ms\n",
      "2026-08-19 06:59:27,771 - INFO - fulqrum.core.linear_operator - Initializing SubspaceHamiltonian\n",
      "2026-08-19 06:59:27,771 - INFO - fulqrum.core.linear_operator - Number of qubits: 12\n",
      "2026-08-19 06:59:27,771 - INFO - fulqrum.core.linear_operator - Num. diagonal terms 78\n",
      "2026-08-19 06:59:27,772 - INFO - fulqrum.core.linear_operator - Num. off-diagonal terms 552\n",
      "2026-08-19 06:59:27,772 - INFO - fulqrum.core.qubit_operator - Term grouping time: 0.076 ms\n",
      "2026-08-19 06:59:27,772 - INFO - fulqrum.core.linear_operator - Term grouping time: 0.344 ms\n",
      "2026-08-19 06:59:27,773 - INFO - fulqrum.core.qubit_operator - Starting ladder int grouping, ladder_width = 2\n",
      "2026-08-19 06:59:27,773 - INFO - fulqrum.core.qubit_operator - Ladder int grouping time: 0.096 ms\n",
      "2026-08-19 06:59:27,773 - INFO - fulqrum.core.linear_operator - Num. off-diagonal groups: 83\n",
      "2026-08-19 06:59:27,774 - INFO - fulqrum.core.spmv - Initializing FulqrumSpMV\n",
      "2026-08-19 06:59:27,774 - INFO - fulqrum.core.spmv - Operator is real\n",
      "2026-08-19 06:59:27,775 - INFO - fulqrum.core.spmv - Operator type = 2\n",
      "2026-08-19 06:59:27,776 - INFO - fulqrum.core.spmv - FulqrumSpMV total init time: 1.683 ms\n",
      "2026-08-19 06:59:27,776 - INFO - fulqrum.core.linear_operator - SubspaceHamiltonian total init time: 4.945 ms\n"
     ]
    }
   ],
   "source": [
    "fop = fq.FermionicOperator.from_json(\"./data/lih.json\")\n",
    "op = fop.extended_jw_transformation()\n",
    "\n",
    "counts = []\n",
    "for kk in range(2**op.width):\n",
    "    counts.append(bin(kk)[2:].zfill(op.width))\n",
    "\n",
    "S = fq.Subspace([counts])\n",
    "Hsub = fq.SubspaceHamiltonian(op, S)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "a30c27e6-6fcc-4933-8bf8-f912d14fe116",
   "metadata": {},
   "outputs": [],
   "source": []
  }
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