calc_compound_interest.ipynb

calc_compound_interest.ipynb

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  "metadata": {
    "colab": {
      "name": "calc_compound_interest.ipynb",
      "provenance": [],
      "authorship_tag": "ABX9TyP6Vq/bEQXag2tVQu/JgZC6",
      "include_colab_link": true
    },
    "kernelspec": {
      "name": "python3",
      "display_name": "Python 3"
    },
    "language_info": {
      "name": "python"
    }
  },
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "view-in-github",
        "colab_type": "text"
      },
      "source": [
        "<a href=\"https://colab.research.google.com/gist/messefor/762f7447c1f5a90574d14f68f64d032d/calc_compound_interest.ipynb\" target=\"_parent\"><img src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open In Colab\"/></a>"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "x5sQMaF6SYxT"
      },
      "source": [
        "複利の計算\n"
      ]
    },
    {
      "cell_type": "code",
      "metadata": {
        "id": "5JhmlwGKST_K"
      },
      "source": [
        "def comp_interest_return(b, n, r, a=0):\n",
        "  '''Compound interest calculation\n",
        "  \n",
        "  b: Original principal amount　元本\n",
        "  n: Years 年数\n",
        "  r: Real interest rate(Annual) 実質年利\n",
        "  a: Amount put aside 年間積立額\n",
        "  '''\n",
        "  R = 1 + r\n",
        "  return R * a * (R ** n - 1) / (R - 1) + (b - a) * R ** n"
      ],
      "execution_count": 2,
      "outputs": []
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "niKMgdu_SsU1"
      },
      "source": [
        "積立額が0の場合、`a=0`で計算"
      ]
    },
    {
      "cell_type": "code",
      "metadata": {
        "colab": {
          "base_uri": "https://localhost:8080/"
        },
        "id": "DPnp7uGUSoQd",
        "outputId": "4f28bdd4-9933-41fc-9102-a33bd8576d5c"
      },
      "source": [
        "b = 1000000  # 元本 100万円\n",
        "r = 0.05  # 5%\n",
        "n = 10 # 10年\n",
        "\n",
        "ret = comp_interest_return(b, n, r, a=0)\n",
        "print(f'元本:{b}円 実質年利:{r * 100:.1f}%, {n}年')\n",
        "print(f'{ret:.0f}円')"
      ],
      "execution_count": 6,
      "outputs": [
        {
          "output_type": "stream",
          "name": "stdout",
          "text": [
            "元本:1000000円 実質年利:5.0%, 10年\n",
            "1628895円\n"
          ]
        }
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "Cjy_hEtuUF6V"
      },
      "source": [
        "元本と積立額が異なる場合`a!=b`"
      ]
    },
    {
      "cell_type": "code",
      "metadata": {
        "colab": {
          "base_uri": "https://localhost:8080/"
        },
        "id": "-pCN27GvUOpn",
        "outputId": "e56b7039-270e-4acf-e4e5-15cb6b3cf1f9"
      },
      "source": [
        "b = 1000000  # 元本 100万円\n",
        "a = 100000  # 毎年 10万円積み立て\n",
        "r = 0.05  # 5%\n",
        "n = 10 # 10年\n",
        "\n",
        "ret = comp_interest_return(b, n, r, a)\n",
        "print(f'元本:{b}円, 積立額:{a}円/年, 実質年利:{r * 100:.1f}%, {n}年')\n",
        "print(f'{ret:.0f}円')"
      ],
      "execution_count": 9,
      "outputs": [
        {
          "output_type": "stream",
          "name": "stdout",
          "text": [
            "元本:1000000円, 積立額:100000円/年, 実質年利:5.0%, 10年\n",
            "2786684円\n"
          ]
        }
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "WERNeJa7Tmci"
      },
      "source": [
        "元本と積立額が同じ場合`a=b`\n",
        "\n"
      ]
    },
    {
      "cell_type": "code",
      "metadata": {
        "colab": {
          "base_uri": "https://localhost:8080/"
        },
        "id": "tSr-u-iKTHZ9",
        "outputId": "2bfc1c5f-f86c-4c5a-861c-61ab82cf93e1"
      },
      "source": [
        "b = 100000  # 元本 10万円\n",
        "a = 100000  # 毎年 10万円積み立て\n",
        "r = 0.05  # 5%\n",
        "n = 10 # 10年\n",
        "\n",
        "ret = comp_interest_return(b, n, r, a)\n",
        "print(f'元本:{b}円, 積立額：{a}円/年 実質年利:{r * 100:.1f}%, {n}年')\n",
        "print(f'{ret:.0f}円')"
      ],
      "execution_count": 10,
      "outputs": [
        {
          "output_type": "stream",
          "name": "stdout",
          "text": [
            "元本:100000円, 積立額：100000円/年 実質年利:5.0%, 10年\n",
            "1320679円\n"
          ]
        }
      ]
    },
    {
      "cell_type": "code",
      "metadata": {
        "id": "zlBrIYpYUCPQ"
      },
      "source": [
        ""
      ],
      "execution_count": null,
      "outputs": []
    }
  ]
}