My question is why does,
import math
a = math.sqrt(3)
area = a * (1 / 2)
print area
give an output of 0.0, but,
import math
a = math.sqrt(3)
area = a / 2
print area
give an output of 0.866025403784
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Matthias
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userphys107
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sorry about the formatting, it said if I indent 8 spaces it formats as code?? – userphys107 Jan 07 '17 at 05:55
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so the difference in the two examples is a/2 as oppossed to a*(1/2), and I'm using sublime btw – userphys107 Jan 07 '17 at 05:56
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Because 1/2 is 0 in Python. Integer division. In the second example one operand is float so float division is done – Andrew Li Jan 07 '17 at 05:58
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Andrew Li - you're right, when I multiplied by 0.5 it gave desired output, thanks for your help! – userphys107 Jan 07 '17 at 06:04
2 Answers
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Actually this is a problem of integer truncation in 2.X.
X / Y Classic and true division. In Python 2.X, this operator performs classic division, truncating results for integers, and keeping remainders (i.e., fractional parts) for floating-point numbers. In 2.X, the / does classic division, performing truncating integer division if both operands are integers and float division (keeping remainders) otherwise.
In Python 3.X, it performs true division, always keeping remainders in floating-point results, regardless of types. In 3.X, the / now always performs true division, returning a float result that includes any remainder, regardless of operand types.
In Python 2.X You can "fix" this by adding from __future__ import division to your script. This will always perform a float division when using the / operator and use // for integer division.
But you can make at least one of the operands in the division is a float, you'll get a float result.
>>> from __future__ import division
area=a*(1/2) area 0.8660254037844386
I hope this will help you.
varshneydevansh
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i think you are using python 2.7 this is the problem with python 2.7 it evaluate 1/2 as zero because it think 1&&2 both as integer so it gives result as integer but in second case your math.sqrt() function return an double value so it gives result as double . but if you use python 3.0 the problem is fixed you get same result in both the cases you can try it it gives 1/2 as 0.5 .
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