{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# How to generate error bars for 2Q-GST\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import pygsti\n",
    "import time\n",
    "\n",
    "#If we were using MPI\n",
    "# from mpi4py import MPI\n",
    "# comm = MPI.COMM_WORLD\n",
    "comm = None\n",
    "\n",
    "#Load the 2-qubit results (if you don't have this directory, run the 2Q-GST example)\n",
    "results = pygsti.io.read_results_from_dir(\"example_files/My2QExample\", \"StandardGST\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "scrolled": true,
    "tags": []
   },
   "outputs": [],
   "source": [
    "# error bars in reports require the presence of a fully-initialized\n",
    "# \"confidence region factory\" within the relevant Estimate object.\n",
    "# In most cases \"fully-initialized\" means that a Hessian has been \n",
    "# computed and projected onto the non-gauge space.\n",
    "\n",
    "# Choose forward simulator and how computation should be split up. Here are a couple examples:\n",
    "#results.estimates['CPTP'].models['stdgaugeopt'].sim = pygsti.forwardsims.MapForwardSimulator(num_atoms=100)\n",
    "results.estimates['CPTPLND'].models['stdgaugeopt'].sim = pygsti.forwardsims.MatrixForwardSimulator(param_blk_sizes=(30,30))\n",
    "\n",
    "# initialize a factory for the 'go0' gauge optimization within the 'default' estimate\n",
    "crfact = results.estimates['CPTPLND'].add_confidence_region_factory('stdgaugeopt', 'final')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "scrolled": true,
    "tags": [
     "nbval-skip"
    ]
   },
   "outputs": [],
   "source": [
    "crfact.compute_hessian(comm=comm, mem_limit=3.0*(1024.0)**3) #optionally use multiple processors & set memlimit\n",
    "crfact.project_hessian('intrinsic error')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Note above cell was executed for demonstration purposes, and was **keyboard-interrupted intentionally** since it would have taken forever on a single processor."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "tags": [
     "nbval-skip"
    ]
   },
   "outputs": [],
   "source": [
    "#write results back to disk\n",
    "results.write()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3 (ipykernel)",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.9.13"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 4
}