the same old "prime numbers" question

[trillianx]

I know there has been lot of discussion on Prime numbers program but I have very specific question. Here is my program:

# Find the prime numbers
# This is a user input program that lets you decide if a number is a prime or not
 
import math
 
num = int(raw_input("Please enter a number: "))
#num = int(math.sqrt(num))
 
 
for i in range(2,math.sqrt(num)):
#for i in range(2,num/2):
    prime = num%i
    if prime == 0.0:
        print "It is not a prime"
        break
    else:
        print "It is a prime"
        break
 

1) I get an error saying the following:

Warning (from warnings module):
File "/Users/trillian/Documents/programs:documents/python programs/Chapter 4/prime", line 10
for i in range(2,math.sqrt(num)):
DeprecationWarning: integer argument expected, got float

Now does range takes ONLY integers or can it take float as well?

2) If you test my program it works well, but it gives "9" as a prime. :-(

3) How do I loop such that I do not need to use "break" statement and still it tells me if a number is a prime or not?

Thanks a lot.

[bartonc]

I know there has been lot of discussion on Prime numbers program but I have very specific question. Here is my program:

# Find the prime numbers
# This is a user input program that lets you decide if a number is a prime or not
 
import math
 
num = int(raw_input("Please enter a number: "))
#num = int(math.sqrt(num))
 
 
for i in range(2,math.sqrt(num)):
#for i in range(2,num/2):
    prime = num%i
    if prime == 0.0:
        print "It is not a prime"
        break
    else:
        print "It is a prime"
        break
 

1) I get an error saying the following:

Warning (from warnings module):
File "/Users/trillian/Documents/programs:documents/python programs/Chapter 4/prime", line 10
for i in range(2,math.sqrt(num)):
DeprecationWarning: integer argument expected, got float

Now does range takes ONLY integers or can it take float as well?

2) If you test my program it works well, but it gives "9" as a prime. :-(

3) How do I loop such that I do not need to use "break" statement and still it tells me if a number is a prime or not?

Thanks a lot.

>>> i = 2.5
>>> for j in range(i):
... print j
...
<string>:1: DeprecationWarning: integer argument expected, got float
0
1
>>>
It's funny that the docs don't mention anything about this.

For floating point ranges you'll need to use the numpy (I think - i don't have my book handy) module.

Clearly, your alorithm needs to know about more than just the integer parts of the range.

a google search for "python float range" turned up this slew of stuff.

[bvdet]

I know there has been lot of discussion on Prime numbers program but I have very specific question. Here is my program:

# Find the prime numbers
# This is a user input program that lets you decide if a number is a prime or not
 
import math
 
num = int(raw_input("Please enter a number: "))
#num = int(math.sqrt(num))
 
 
for i in range(2,math.sqrt(num)):
#for i in range(2,num/2):
    prime = num%i
    if prime == 0.0:
        print "It is not a prime"
        break
    else:
        print "It is a prime"
        break
 

1) I get an error saying the following:

Warning (from warnings module):
File "/Users/trillian/Documents/programs:documents/python programs/Chapter 4/prime", line 10
for i in range(2,math.sqrt(num)):
DeprecationWarning: integer argument expected, got float

Now does range takes ONLY integers or can it take float as well?

2) If you test my program it works well, but it gives "9" as a prime. :-(

3) How do I loop such that I do not need to use "break" statement and still it tells me if a number is a prime or not?

Thanks a lot.

'range()' expects an integer. I modified your code a bit:

import math
 
def is_prime():
    num = int(raw_input("Please enter a number: "))
    for i in range(2,int(math.ceil(num**0.5))):
        if num % i == 0:
            print "%s is not a prime" % (num)
            return False
    print "%s is a prime" % (num)
    return True
 
is_prime()

Here's another version:

def is_prime(n):
    count = 2
    while count < n**0.5:
        if n % count == 0:
            print '%d is a product of %d and %d' % (n, count, n/count)
            return False
        count += 1
    print n, 'is a prime number'
    return True

[ghostdog74]

It's funny that the docs don't mention anything about this.

hi, hmm..i think it does. Here . it says "arguments must be plain integers".

[bartonc]

hi, hmm..i think it does. Here . it says "arguments must be plain integers".

Yeah. By "that" I meant "DeprecationWarning".

[ghostdog74]

Yeah. By "that" I meant "DeprecationWarning".

oh i see..lol..:):):)