{
  "nbformat": 4,
  "nbformat_minor": 0,
  "metadata": {
    "colab": {
      "provenance": [],
      "collapsed_sections": []
    },
    "kernelspec": {
      "name": "python3",
      "display_name": "Python 3"
    },
    "language_info": {
      "name": "python"
    }
  },
  "cells": [
    {
      "cell_type": "code",
      "source": [
        "# Import Libraries\n",
        "import numpy as np\n",
        "import pandas as pd"
      ],
      "metadata": {
        "id": "aDtFkeqAvLX2"
      },
      "execution_count": 132,
      "outputs": []
    },
    {
      "cell_type": "code",
      "execution_count": 133,
      "metadata": {
        "id": "Letb52yp47Gb"
      },
      "outputs": [],
      "source": [
        "# Define RouthStability Class \n",
        "class RouthStability():\n",
        "  ## constructor takes string of coefficiens from polynomial\n",
        "  def __init__(self, den):\n",
        "    self.den = np.array([float(item) for item in den.split()])\n",
        "    self.deg = len(self.den)\n",
        "  ## append k as constant in array\n",
        "  def set_k(self, k):\n",
        "    self.den = np.append(self.den, float(k))\n",
        "    self.deg += 1\n",
        "  ## generate routh table and print its state\n",
        "  def calc_routh(self):\n",
        "    height = (self.deg+1)//2\n",
        "    arr = np.zeros((height + 2,height))\n",
        "    for index in range(self.deg):\n",
        "      if index % 2 == 0:\n",
        "        arr[0][index//2] = self.den[index]\n",
        "      else:\n",
        "        arr[1][(index-1)//2] = self.den[index]\n",
        "\n",
        "    for i in range(2, height+2):\n",
        "      for j in range(height-1):\n",
        "        arr[i][j] = (arr[i-1][0]*arr[i-2][j+1] - arr[i-2][0]*arr[i-1][j+1])//2\n",
        "        arr[i][j] += 0\n",
        "    \n",
        "    self.df = pd.DataFrame(arr)\n",
        "    self.show_tab()\n",
        "    if self.is_stable() == True:\n",
        "      print(\"SYSTEM IS STABLE\")\n",
        "    else:\n",
        "      print(\"SYSTEM IS UNSTABLE\")\n",
        "  ## print generated route table\n",
        "  def show_tab(self):\n",
        "    print(self.df)\n",
        "  ## return generated route DataFrame\n",
        "  def get_table(self):\n",
        "    return self.df\n",
        "  ## return system stability as boolean\n",
        "  def is_stable(self):\n",
        "    flag = True\n",
        "    for item in self.df[0]:\n",
        "      if item < 0: flag = False\n",
        "    return flag\n",
        "  ## return the value of a polynomial\n",
        "  def get_poly(self, x):\n",
        "    total = 0\n",
        "    for i in range(self.deg):\n",
        "      total += self.den[self.deg-i-1]*(x**i)\n",
        "      print(total)\n",
        "    return total"
      ]
    },
    {
      "cell_type": "code",
      "source": [
        "# First Testing\n",
        "den = input(\"Enter your polynomial: \")\n",
        "k_in = input(\"Enter your K: \")\n",
        "\n",
        "rs = RouthStability(den)\n",
        "rs.set_k(k_in)\n",
        "rs.calc_routh()"
      ],
      "metadata": {
        "id": "Je19fGrvtOu4",
        "colab": {
          "base_uri": "https://localhost:8080/"
        },
        "outputId": "c99b1159-f745-4c3f-c012-c2f464b8edb0"
      },
      "execution_count": 134,
      "outputs": [
        {
          "output_type": "stream",
          "name": "stdout",
          "text": [
            "Enter your polynomial: 1 2 3 4 5\n",
            "Enter your K: 6\n",
            "     0    1    2\n",
            "0  1.0  3.0  5.0\n",
            "1  2.0  4.0  6.0\n",
            "2  1.0  2.0  0.0\n",
            "3  0.0  3.0  0.0\n",
            "4 -2.0  0.0  0.0\n",
            "SYSTEM IS UNSTABLE\n"
          ]
        }
      ]
    },
    {
      "cell_type": "code",
      "source": [
        "# Second Testing\n",
        "den = input(\"Enter your polynomial: \")\n",
        "k_in = input(\"Enter your K: \")\n",
        "\n",
        "rs = RouthStability(den)\n",
        "rs.set_k(k_in)\n",
        "rs.calc_routh()"
      ],
      "metadata": {
        "colab": {
          "base_uri": "https://localhost:8080/"
        },
        "id": "kFgcxNcscafI",
        "outputId": "25aadcc4-6a29-4c16-c992-46d95a56cbfb"
      },
      "execution_count": 136,
      "outputs": [
        {
          "output_type": "stream",
          "name": "stdout",
          "text": [
            "Enter your polynomial: 12 56 37 80\n",
            "Enter your K: 17\n",
            "           0      1     2\n",
            "0       12.0   37.0  17.0\n",
            "1       56.0   80.0   0.0\n",
            "2      556.0  476.0   0.0\n",
            "3     8912.0    0.0   0.0\n",
            "4  2121056.0    0.0   0.0\n",
            "SYSTEM IS STABLE\n"
          ]
        }
      ]
    },
    {
      "cell_type": "code",
      "source": [
        "# Third Testing\n",
        "den = input(\"Enter your polynomial: \")\n",
        "k_in = input(\"Enter your K: \")\n",
        "\n",
        "rs = RouthStability(den)\n",
        "rs.set_k(k_in)\n",
        "rs.calc_routh()"
      ],
      "metadata": {
        "colab": {
          "base_uri": "https://localhost:8080/"
        },
        "id": "jaif_A4_hfeJ",
        "outputId": "0b387e7e-efbf-4f5c-fb45-d98489bbba3e"
      },
      "execution_count": 137,
      "outputs": [
        {
          "output_type": "stream",
          "name": "stdout",
          "text": [
            "Enter your polynomial: 1.2 6.81 7.31\n",
            "Enter your K: 3.141\n",
            "       0      1\n",
            "0   1.20  7.310\n",
            "1   6.81  3.141\n",
            "2  23.00  0.000\n",
            "3  36.00  0.000\n",
            "SYSTEM IS STABLE\n"
          ]
        }
      ]
    },
    {
      "cell_type": "code",
      "source": [],
      "metadata": {
        "id": "SjkQCR9chk6P"
      },
      "execution_count": null,
      "outputs": []
    }
  ]
}