The idea behind this project is is to create a scientific calculator which will be easy to use by any user. Anyone can execute from the very basic arithmetic operations to some more complex mathematical functions.

Import libraries

In order to avoid the full use of a Python editor or a command line window, we are going to create a basic GUI.
The Tkinter package (“Tk interface”) is the standard Python interface to the Tcl/Tk GUI toolkit. Read more about the package here.

We also use math and numpy libraries in order to build basic mathematical functions (sin, cosine, log, ...)

from tkinter import *
import math
import numpy as np

GUI Creation-Initialization

At first we build the general structure of the GUI which will contain the buttons.

tk_calc = Tk ()
tk_calc.configure (bg = "# 293C4A", bd = 10) # Background color and padding
tk_calc.title ("Scientific Calculator")      # GUI title

Functions

We define some necessary mathematical functions which we are going to use inside our functions' buttons. For example percent() function finds the result of the division of a number by 100.

def percent():
    global calc_operator
    temp = str(eval(calc_operator+'/100'))
    calc_operator = temp
    text_input.set(temp)

We also define some functions for the correct operations of our calulator. For example we define button_delete() function which we are using for the DEL button. This function allows user to delete one by one from the end to start the digits that have been entered inside the calculator's entry screen.

def button_delete():
    global calc_operator
    text = calc_operator[:-1]
    calc_operator = text
    text_input.set(text)

Button construction

Now it is time to fill our calculator with buttons. We place one button for each function, each operation and for each one of the 10 digits (0 to 9). The basic syntax of a Tkinter button is the following.

button = Button(container, *options)

In order to place each row of buttons we are using grid method.
For examplel the 7th row of our calculator containing digits 4,5,6 and the operators *,/ .

button_4 = Button(tk_calc, button_params_main, text='4', command=lambda:button_click('4')).grid(row=7, column=0, sticky="nsew")
button_5 = Button(tk_calc, button_params_main, text='5', command=lambda:button_click('5')).grid(row=7, column=1, sticky="nsew")
button_6 = Button(tk_calc, button_params_main, text='6', command=lambda:button_click('6')).grid(row=7, column=2, sticky="nsew")
mul = Button(tk_calc, button_params_main, text='*', command=lambda:button_click('*')).grid(row=7, column=3, sticky="nsew")
div = Button(tk_calc, button_params_main, text='/', command=lambda:button_click('/')).grid(row=7, column=4, sticky="nsew")

Some explanations for each button and the function which represents are the following :

1st Row

abs	The absolute value of a number (e.g. abs(-5) = 5)
mod	From modulo. it's the operation to find the remainder of the division of one number by another. In python we use the symbol % (e.g. 5mod2 = 5%2 = 1)
div	Floor division returns the result of the division rounded down to the nearest integer. In python we use the symbol // (e.g. 8div3 = 8//3 = 2)
x!	The factorial of the number x (e.g. 4! = 24)
e	The Euler's number. A mathematical constant approximately equal to 2.71828

2nd Row

sin	Sine of an angle θ in degrees (e.g. sin(90)=1)
cos	Cosine of an angle θ in degrees (e.g. cos(180)=-1)
tan	Tangent of an angle θ in degrees (e.g. tan(45)=1)
cot	Cotangent of an angle θ in degrees (e.g. cot(45) = 1/tan(45) = 1)
π	Archimedes' constant defined as the ratio of a circle's circumference to its diameter. It is approximately equal to 3.14159.

3rd Row

x2	x raised to the power of 2 (e.g. 42 = 16)
x3	x raised to the power of 3 (e.g. 53 = 125 )
xn	x raised to any power (e.g. 24 = 16 )
x-1	x raised to the power of (-1). The inverse of number x (e.g. 2-1 = 0.5)
10x	Powers of 10 (e.g. 103 = 1000)

4th Row

2√	Square root of a number (e.g. 2√144 = 12)
∛	Cube root of a number (e.g. ∛8 = 2)
n√	Any root of a number (e.g. bbbb∜16 = 2)
log10	The logarithm of a number with base 10 (e.g. log101000 = 3)
ln	The logarithm of a number with base e (e.g. logee = ln e = 1)

5th Row

(	Left parenthesis
)	Right parenthesis
±	Change the sign of a number
%	Find the percentage of a number (e.g. 5% = 0.05)
ex	Expotential function (e.g. e2=approx 7.389 )

6th, 7th, 8th, 9th Row

The basic number buttons (0 to 9)
The basic math symbols (operators) (+, -, *, /)
The equal sign (=) and point (.)
DEL	Button to delete one or more from the end of the entrY
AC	Button to delete the whole entry
EXP	Multiply any number with powers of 10 (e.g. 2 * 10 ** 3 = 2000)

Tkinter mainloop

The method mainloop plays a vital role in Tkinter as it is a core application that waits for events and helps in updating the GUI or in simple terms, we can say it is event-driven programming. If no mainloop() is used then nothing will appear on the screen window .