comparing floating numbers in unix - unix

Question

I am facing problem in comparing big floating variables in unix
Code:
error message: syntax error on line 1 teletype
I got to know from one of the old posts in the forum this is because
"the script is trying to do a calculation with bc by echoing an expression into it. But one of the variables has an illegal number"
Below is the script which is giving the error
Code:
#! /bin/bash -xv
a=`cat abc.csv | sed '1d' | tr -s ' ' | cut -d, -f3`
echo $a
-180582621617.24
b=`sed '1d' def.csv | cut -d',' -f7 | awk '{s+=$1}END{ printf("%.2f\n",s)}'`
echo $b
-180582621617.37
Result=`echo "if($a !=$b) 1" | bc `
if [ $Result -eq 1 ]; then
echo "both values not equal"
else
echo " both values equal"
fi
But I was able to compare it when hard-coded
Code:
a=`echo "-180582621617.24,222.555,333.333" | awk -F"," '{print $1}'`
b=`echo "-180582621617.24,222.555,333.333" | awk -F"," '{print $1}'`
Result=`echo "if($a !=$b) 1" | bc `
if [ $Result -eq 1 ]; then
echo "both values not equal"
else
echo " both values equal"
fi

Answer 1

Your test in bc is return 1 if true and nothing when false.
$Result will be then either undefined or numeric (1). test with -eq only works with two operands both numeric. Just return 0 for the else case
Result=`echo "if($a !=$b) 1 else 0" | bc `
if [ $Result -eq 1 ] ; then
echo "both values not equal"
else
echo " both values equal"
fi

Answer 2

Use bc for dealing with floating numbers in shell:
$ bc <<< '-180582621617.24 == -180582621617.37'
0
$ bc <<< '-180582621617.24 != -180582621617.37'
1
In your case, it is going to be bc <<< "$a != $b", e.g.:
[[ bc <<< "$a != $b" ]] && Result=1 || Result=0

Answer 3

Thanks for all the suggestions.
I was able to compare by creating two temp files and using the diff -w command.
#! /bin/bash -xv
rm -f triger_cksum.txt data_cksum.txt
a=`cat ab.csv | sed '1d' | tr -s ' ' | cut -d, -f3`
echo $a > triger_cksum.txt
b=`sed '1d' cd.csv | cut -d',' -f61 | awk '{s+=$1}END{ printf("%.6f\n",s)}'`
echo $b > data_cksum.txt
diff_files=`diff -w triger_cksum.txt data_cksum.txt | wc -l | tr -s ' '`
if [ $diff_files -eq 0 ]
then
echo "cksum equal"
else
echo "cksum not equal"
fi