{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "# PyOpenCL: Experimenting in IPython"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "from __future__ import division\n",
        "import numpy as np\n",
        "import pyopencl as cl\n",
        "import pyopencl.array"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Load the PyOpenCL IPython extension:"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 2,
      "metadata": {
        "collapsed": false
      },
      "outputs": [
        {
          "name": "stderr",
          "output_type": "stream",
          "text": [
            "/usr/lib/python3/dist-packages/IPython/utils/traitlets.py:504: DeprecationWarning: inspect.getargspec() is deprecated, use inspect.signature() instead\n",
            "  argspec = inspect.getargspec(c)\n"
          ]
        }
      ],
      "source": [
        "%load_ext pyopencl.ipython_ext"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Create an OpenCL context and a command queue:"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 3,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "ctx = cl.create_some_context()\n",
        "queue = cl.CommandQueue(ctx)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "## Using the kernel 'magic'\n",
        "\n",
        "Define an OpenCL kernel using the `%%cl_kernel` magic:"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 4,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "%%cl_kernel\n",
        "\n",
        "__kernel void sum_vector(__global const float *a,\n",
        "__global const float *b, __global float *c)\n",
        "{\n",
        "  int gid = get_global_id(0);\n",
        "  c[gid] = a[gid] + b[gid];\n",
        "}"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "This looks for `cl_ctx` or `ctx` in the user namespace to find a PyOpenCL context.\n",
        "\n",
        "Kernel names are automatically injected into the user namespace, so we can just use `sum_vector` from Python below.\n",
        "\n",
        "Now create some data to work on:"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 5,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "n = 10000\n",
        "\n",
        "a = cl.array.empty(queue, n, dtype=np.float32)\n",
        "a.fill(15)\n",
        "\n",
        "b_host = np.random.randn(n).astype(np.float32)\n",
        "b = cl.array.to_device(queue, b_host)\n",
        "\n",
        "c = cl.array.empty_like(a)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Run the kernel:"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 6,
      "metadata": {
        "collapsed": false
      },
      "outputs": [
        {
          "data": {
            "text/plain": [
              "<pyopencl.cffi_cl.Event at 0x7f48c1df4ba8>"
            ]
          },
          "execution_count": 6,
          "metadata": {},
          "output_type": "execute_result"
        }
      ],
      "source": [
        "sum_vector(queue, (n,), None, a.data, b.data, c.data)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Check the result using `numpy` operations:"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 7,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "assert (c.get() == b_host + 15).all()"
      ]
    }
  ],
  "metadata": {
    "kernelspec": {
      "display_name": "Python 3",
      "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": "3.5.0+"
    }
  },
  "nbformat": 4,
  "nbformat_minor": 0
}