Unix Tip: ARITHMETIC COMPARISON

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UNIX GURU UNIVERSE
UNIX HOT TIP

Unix Tip 3316 - March 9, 2011

http://www.ugu.com/sui/ugu/show?tip.today

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ARITHMETIC COMPARISON

In UNIX shell arithmetic comparison
is limited to integer values. Here
is a tip to compare floating values
using basic shell commands.

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#! /bin/sh
# test shell script
n1="01.401"
n2="01.350"

function compareFloatSmall
{
sort -n <<: | head -1
$n1
$n2
:
}

function compareFloatGreat
{
sort -r -n <<: | head -1
$n1
$n2
:
}

small=$(compareFloatSmall $n1 $n2)
echo "Comparing $n1 to $n2: smaller $less"
great=$(compareFloatGreat $n1 $n2)
echo "Comparing $n1 to $n2: greater $great"

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Alternatively you can use a small 'awk' program.

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#! /bin/sh
# A couple of examples in awk.
n1="03.550"
n2="02.550"

echo "$n1 $n2" | awk '{
if ( $1 >= $2 ) print $1
if ( $1 <= $2 ) print $2
if ( $1 > $2 ) print $1
if ( $1 < $2 ) print $2
if ( $1 == $2 ) print $1, $2
}'
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This tip generously supported by: sthackeray@netscape.net

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