fp.py

#!/usr/bin/env python3
from sympy import var
from sympy import sympify
from math import *
import sys
from prettytable import PrettyTable
import time


# Value from function
def f(value):

    res = expr.subs(x, value)
    return res


# False Position Method
def false_position(xu, xl):
    atas = xu*f(xl)-xl*f(xu)
    bawah = f(xl)-f(xu)
    xm = atas/bawah
    return xm


# Input
x = var('x')

try:
    user_input = input("Enter the function (3*x**2+2*x+2) = ")
    expr = sympify(user_input)
except:
    print("input yang anda masukkan tidak sesuai")
    sys.exit()

try:
    xl = float(input("Enter the value of Xl (-10) = "))
except:
    print("input yang anda masukkan tidak sesuai")
    sys.exit()

try:
    xu = float(input("enter the value of xu (15) = "))
except:
    print("input yang anda masukkan tidak sesuai")
    sys.exit()

if(f(xl)*f(xu) < 0):
    success = 1
else:
    print("Pastikan nilai F(xl) dan F(xu) berlawanan tanda")
    sys.exit()

try:
    RAE = float(input("Enter the value of Aproximation Error (0.0001) = "))
except:
    print("input yang anda masukkan tidak sesuai")
    sys.exit()

RAE_now = 100
counter = 0
x_old = 0

# Definition Table
t = PrettyTable()
t.field_names = ["i", "xi", "Aproximation Error", 'f(xl)', 'f(xu)', 'f(xm)']

start = time.time()
try:
    # looping
    while RAE < RAE_now:

        xm = false_position(xl, xu)
        diff = f(xl)*f(xm)
        xu_old = xu
        xl_old = xl

        if(diff < 0):
            xu = xm
        elif(diff > 0):
            xl = xm
        elif(diff == 0):
            print("True Value = "+str(xm)+".")
            sys.exit()
        else:
            print("Program Error")
            sys.exit()
        if(counter == 0):
            x_new = xm
            t.add_row([counter, x_new, "-", f(xl_old), f(xu_old), f(xm)])
            counter = counter+1
            x_old = x_new
            continue
        x_new = xm
        selisih = abs(x_new-x_old)
        RAE_now = abs(selisih/x_new)
        t.add_row([counter, x_new, RAE_now, f(xl_old), f(xu_old), f(xm)])
        x_old = x_new
        counter = counter+1
except:
    print("Program Error")
    sys.exit()
end = time.time()


print(t)
print("Waktu yang dibutuhkan adalah "+str(end-start)+" detik")