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Shell Programming and Scripting

Arithmetic but keep 2 decimal places

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# 1  
Old 02-11-2013
Arithmetic but keep 2 decimal places
I am trying to perform arithmetric, for example, to increment the value of variable $a (say 3) by 0.05 but when I tried the following expression

Code:
let a=a+0.05

or
Code:
a=$((a+0.05))

both returned

Code:
3.0499999999999998

I want to keep 2 decimal places so it returns 3.05 instead.
# 2  
Old 02-11-2013
Code:
a=$(echo "scale=2; 3+0.05" | bc)

# 3  
Old 02-11-2013
Code:
echo 3 | awk '{print $0+0.05}'
3.05

Code:
a=$(echo $a | awk '{print $0+0.05}')

# 4  
Old 02-11-2013
Hi.
Code:
printf "%s %.2f\n" $a $a
3.0499999999999998 3.05

Best wishes ... cheers, drl
# 5  
Old 02-11-2013
Quote:
Originally Posted by drl
Hi.
Code:
printf "%s %.2f\n" $a $a
3.0499999999999998 3.05

Best wishes ... cheers, drl
This just clean up the mess not the source of the problem.
Using awk or bc and you get correct result.
# 6  
Old 02-11-2013
Quote:
Originally Posted by Jotne
This just clean up the mess not the source of the problem.
Using awk or bc and you get correct result.
It works on your system in your case but this is not guaranteed. It uses floating point numbers too, which have the same issues anywhere.

bc, being an arbitrary precision calculator, can indeed give you the exact result, though fiddling is necessary to prevent it stripping off the decimal points.
# 7  
Old 02-12-2013
Thanks everyone!
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