How to implement pow(x) and sqrt(x)?

Question

I tried looking for a similar answer, but didn't find anything. So here goes.

I am currently tasked with creating a simple calculator with a GUI in Python using the tkinter tools.

I was almost done when I ran into some problems implementing pow(x) and sqrt(x) and having them work properly.

This is the function I used for my operand buttons:

def press(num):
   global expression
   expression = expression + str(num)
   equation.set(expression)

This worked fine for all the simple stuff like '+':

plus = Button(gui, text=' + ', fg='orange', bg='white', command=lambda: press("+"), height=1, width=7)

But now I still need to add pow and sqrt by importing from math and connect them to the buttons. I tried using the same "press" function, but with sqrt I am getting a ValueError.

powx = Button(gui, text=' pow(x) ', fg='orange', bg='white', command=lambda: press("pow("), height=1, width=7)
powx.grid(row=4, column=4)
sqrt = Button(gui, text=' sqrt(x) ', fg='orange', bg='white', command=lambda: press("sqrt("), height=1, width=7)
sqrt.grid(row=5, column=4)

sqrt Error Code: TypeError: 'Button' object is not callable

Equals:

def equalpress():
    try:
        global expression
        total = str(eval(expression))
        equation.set(total)
        expression = ""

    except ZeroDivisionError: 
        equation.set(" Cant divide through Zero! ")
        expression = ""

    except SyntaxError: 
        equation.set(" SyntaxError! ")
        expression = ""

I would really apreciate some advice. Thanks! GUI

Answer 1

The problem is that you're replacing the built-in sqrt() function when you do:

sqrt = Button(gui, text=' sqrt(x) ', fg='orange', bg='white', command=lambda: press("sqrt("), height=1, width=7)
sqrt.grid(row=5, column=4)

Now the name sqrt refers to your button, not the function. Change the variable name, like you do for the pow button.

sqrtx = Button(gui, text=' sqrt(x) ', fg='orange', bg='white', command=lambda: press("sqrt("), height=1, width=7)
sqrtx.grid(row=5, column=4)