So I'm supposed to create a code that calculates the cube root of an inputted number with the approximation of up to 2 decimal places. This code above calculates the square root of a number with up to 2 decimal places:
epsilon = 0.01
guess = num/2.0
while abs(guess**2 - num) >= epsilon:
guess = guess - abs(guess**2 - num) / (2 * guess)
print("Guess:", guess)
So apparently I am able to do the cube root with that criteria by modifying this code that was given and using this in the code:
delta = abs(guess**3 - num) / 100.0
I tried using that line and modifying the code used for square root and I keep getting:
OverflowError: ('Result too large')
This is what my code looks like so far:
num = float(input("Enter a number: "))
epsilon = 0.01
guess = num/2.0
while abs(guess**3 - num) >= epsilon:
guess = abs(guess - (guess**3 - num)/100.0)
print("Guess:", guess)
When I run that code above this is what happens:
runfile('C:/Users/100617828/Documents/CSCI1040U/edits.py', runfile('C:/Users/100617828/Documents/CSCI1040U/edits.py', wdir='C:/Users/100617828/Documents/CSCI1040U')
Enter a number: 34 Traceback (most recent call last):
File "", line 1, in runfile('C:/Users/100617828/Documents/CSCI1040U/edits.py', wdir='C:/Users/100617828/Documents/CSCI1040U')
File "C:\\Anaconda\\lib\\site-packages\\spyderlib\\widgets\\externalshell\\sitecustomize.py", line 699, in runfile execfile(filename, namespace)
File "C:\\Anaconda\\lib\\site-packages\\spyderlib\\widgets\\externalshell\\sitecustomize.py", line 88, in execfile exec(compile(open(filename, 'rb').read(), filename, 'exec'), namespace)
File "C:/Users/100617828/Documents/CSCI1040U/edits.py", line 11, in while abs(guess**3 - num) >= epsilon:
OverflowError: (34, 'Result too large')
This is what my assignment sheet is telling me to do but it seems I don't need to use delta = abs(guess**3 - num)/100.0
?
The method you are using is called Newton-Raphson approximation , and you should use the first derivative of the function you are trying to solve as the denominator. Because the first derivative of x^3
is 3*x^2
, the iteration line must be:
guess = guess - abs(guess**3 - num) / (3 * guess**2)
See the working code at https://repl.it/DqZA/0
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.