dot vs xpy!.ipynb

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      "warmup\n",
      "  0.000001 seconds (3 allocations: 144 bytes)\n",
      "dot\n",
      "@elapsed(dot(A,B)) = 4.1134e-5\n",
      "@allocated(dot(A,B)) = 16\n",
      "xpy!\n",
      "@elapsed(xpy!(A,B)) = 4.2762e-5\n",
      "@allocated(xpy!(A,B)) = 0\n"
     ]
    }
   ],
   "source": [
    "N = 30_000\n",
    "\n",
    "A0 = randn(N)\n",
    "B = randn(N)\n",
    "\n",
    "# define xpy!\n",
    "function xpy!(A, B)\n",
    "    size(A,1) == (n = size(B,1)) || return A\n",
    "    @inbounds for i = 1:n\n",
    "        A[i] *= B[i]\n",
    "    end\n",
    "    A\n",
    "end\n",
    "\n",
    "println(\"warmup\")\n",
    "@time 1\n",
    "dot(randn(10), randn(10))\n",
    "xpy!(randn(10), randn(10))\n",
    "\n",
    "# measure\n",
    "\n",
    "println(\"dot\")\n",
    "A = copy(A0)\n",
    "gc()\n",
    "@show @elapsed dot(A,B)\n",
    "A = copy(A0)\n",
    "gc()\n",
    "@show @allocated dot(A,B)\n",
    "println(\"xpy!\")\n",
    "A = copy(A0)\n",
    "gc()\n",
    "@show @elapsed xpy!(A,B)\n",
    "A = copy(A0)\n",
    "gc()\n",
    "@show @allocated xpy!(A,B)\n",
    "\n",
    "# suppress output\n",
    "nothing"
   ]
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