How to round up value upto 2 decimal places using sed?

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# 8  
Old 11-15-2013
Dear in2nix4life

but it is not working in below case, output should be "200.92" but it is giving "200.93"



c=`echo "scale=2;($a*$b)+.01" |bc -l`
echo $c

Last edited by Scott; 11-16-2013 at 01:17 AM.. Reason: Code tags
# 9  
Old 11-15-2013
Again, I think 0.005 is the correct value to add, not 0.01. 0.01 will round EVERY number up, 0.005 will only round up by halves. But then bc insists on outputting three or more digits and the number must be truncated after, try my code.
# 10  
Old 11-15-2013
If you really really really insist on a sed solution, try this as a starting point; you will need to extend it for further carry operations:
echo 205.5686 |  sed    's/\(\...\)[0-4].*/\1/;t;

This User Gave Thanks to RudiC For This Post:
# 11  
Old 11-15-2013
Longhand using OSX 10.7.5, default bash terminal.
#!/bin/bash --posix
# Save IFS.
# Number with 3rd decinal place as 6. NOTE: no zero at the start but "-" instead!
# Create an array.
# Ensure a roundup number!
# Print it to the terminal.
printf "%0.2f\n" ${round[0]}.${round[1]:0:2}$roundup
# Repeat above with 3rd decimal place as 3.
printf "%0.2f\n" ${round[0]}.${round[1]:0:2}$roundup
# Reset IFS.
# You now have the building blocks using bash builtins.
# I will leave you to create the required loops.

Last login: Fri Nov 15 18:44:29 on ttys000
AMIGA:barrywalker~> chmod 755
AMIGA:barrywalker~> ./
AMIGA:barrywalker~> _


IMPORTANT! This does NOT account for +ve or -ve _integer_ numbers, zero and
floating point _equivalents_ of _integer_ numbers; so be well aware!

Last edited by wisecracker; 11-15-2013 at 06:06 PM.. Reason: Added a negative number to the code and EDIT...
This User Gave Thanks to wisecracker For This Post:
# 12  
Old 11-16-2013
If you have a large number of such numbers to process, you might be better off using the Korn shell, which has builtin floating point support, because of the overhead in invoking the bc utility.

For example:


c=$(printf "%.2f\n"  $(( a * b ))) 
echo $c

outputs 205.55
This User Gave Thanks to fpmurphy For This Post:
# 13  
Old 11-16-2013
Since I do not like to use bc because its not in all image. And normal I use bash. To do use math I use awk. This should work in most image.
Sed is not tool for math, so I do not see any reason for using that.
c=$(awk -v a=$a -v b=$b 'BEGIN {printf "%.2f\n",a*b}')
echo c$

This User Gave Thanks to Jotne For This Post:
# 14  
Old 11-17-2013
Use bc for calculation, let printf do the rounding!
c=`echo "$a*$b" | bc -l`
printf "%.2f\n" $c

NB you must quote the expression, otherwise the shell tries to match a * against the current directory.
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