Solution/Day_04_Solution_v2.ipynb

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    "# [作業目標]\n",
    "\n",
    "1. [簡答題] 請問下列程式碼，運算結果分別為何？\n",
    "\n",
    "```\n",
    "a = np.array( [20,30,40,50] )\n",
    "b = np.array( [1,2,3,4] ) \n",
    "c = 1\n",
    "d = np.array( [1] )\n",
    "e = np.array( [1,2] ) \n",
    "```\n",
    "\n",
    "2. 如何在不用迴圈的情況下計算 (A+B)*(-A/2) ？那用迴圈怎麼做？\n",
    "\n",
    "3. 請問如何計算「1x6 的單位矩陣」和「6x1 的單位矩陣」的內積和外積？"
   ]
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   "source": [
    "# 作業 "
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 1. [簡答題] 請問下列程式碼，運算結果分別為何？\n",
    "\n",
    "```\n",
    "a = np.array( [20,30,40,50] )\n",
    "b = np.array( [1,2,3,4] ) \n",
    "c = 1\n",
    "d = np.array( [1] )\n",
    "e = np.array( [1,2] ) \n",
    "```\n"
   ]
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     "name": "stdout",
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     "text": [
      "[ 40  60  80 100]\n",
      "[21 32 43 54]\n",
      "[21 31 41 51]\n",
      "[21 31 41 51]\n"
     ]
    },
    {
     "ename": "ValueError",
     "evalue": "operands could not be broadcast together with shapes (4,) (2,) ",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mValueError\u001b[0m                                Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-1-362970a2360d>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[1;32m     11\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0mc\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     12\u001b[0m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0md\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 13\u001b[0;31m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0me\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mValueError\u001b[0m: operands could not be broadcast together with shapes (4,) (2,) "
     ]
    }
   ],
   "source": [
    "import numpy as np\n",
    "\n",
    "a = np.array( [20,30,40,50] )\n",
    "b = np.array( [1,2,3,4] ) \n",
    "c = 1\n",
    "d = np.array( [1] )\n",
    "e = np.array( [1,2] ) \n",
    "\n",
    "print(a + a)\n",
    "print(a + b)\n",
    "print(a + c)\n",
    "print(a + d)\n",
    "print(a + e)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 2. 如何在不用迴圈的情況下計算 (A+B)*(-A/2) ？那用迴圈怎麼做？\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[-1.5 -1.5 -1.5]\n"
     ]
    }
   ],
   "source": [
    "A = np.ones(3)*1\n",
    "B = np.ones(3)*2\n",
    "\n",
    "print((A + B) * (-A / 2))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 3. 請問如何計算「1x6 的單位矩陣」和「6x1 的單位矩陣」的內積和外積？\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 記得先 Import 正確的套件\n",
    "\n",
    "import numpy as np\n"
   ]
  },
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     "text": [
      "[[1. 1. 1. 1. 1. 1.]\n",
      " [1. 1. 1. 1. 1. 1.]\n",
      " [1. 1. 1. 1. 1. 1.]\n",
      " [1. 1. 1. 1. 1. 1.]\n",
      " [1. 1. 1. 1. 1. 1.]\n",
      " [1. 1. 1. 1. 1. 1.]]\n",
      "[[6.]]\n"
     ]
    }
   ],
   "source": [
    "# 參考解答\n",
    "\n",
    "A = np.ones((1,6))\n",
    "B = np.ones((6,1))\n",
    "\n",
    "print(A * B)\n",
    "print(A @ B)"
   ]
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