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Top Forums Shell Programming and Scripting any way to speed up calculations in bash script Post 302276878 by npatwardhan on Wednesday 14th of January 2009 11:27:35 PM
Old 01-15-2009
any way to speed up calculations in bash script

hi i have a script that is taking the difference of multiple columns in a file from a value from a single row..so far i have a loop to do that.. all the data is floating point..fin[i] has the difference between array1 and array2..array1 has 700 x 300= 210000 values and array2 has 700 values..

Code:
while [ $j -lt $outer ];do
b=${ARRAY2[j]}
i=0
while [ $i -lt $count1 ];do
a=${ARRAY1[k]}
fin[i]=`echo $a - $b | bc`
printf "%.1f," ${fin[i]} >> "$count".diff
((i++))
((k++))
done 
echo >> "$count".diff
((j++))
done

i am using bc to calculate the floating point subtraction. problem is i have about 600 columns and 300 rows..the script takes a long time to execute.. is there any way i can speed it up?
 

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ARRAY_INTERSECT_KEY(3)							 1						    ARRAY_INTERSECT_KEY(3)

array_intersect_key - Computes the intersection of arrays using keys for comparison

SYNOPSIS
array array_intersect_key (array $array1, array $array2, [array $...]) DESCRIPTION
array_intersect_key(3) returns an array containing all the entries of $array1 which have keys that are present in all the arguments. PARAMETERS
o $array1 - The array with master keys to check. o $array2 - An array to compare keys against. o $... - A variable list of arrays to compare. RETURN VALUES
Returns an associative array containing all the entries of $array1 which have keys that are present in all arguments. EXAMPLES
Example #1 array_intersect_key(3) example <?php $array1 = array('blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4); $array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan' => 8); var_dump(array_intersect_key($array1, $array2)); ?> The above example will output: array(2) { ["blue"]=> int(1) ["green"]=> int(3) } In our example you see that only the keys 'blue' and 'green' are present in both arrays and thus returned. Also notice that the values for the keys 'blue' and 'green' differ between the two arrays. A match still occurs because only the keys are checked. The values returned are those of $array1. The two keys from the key => value pairs are considered equal only if (string) $key1 === (string) $key2 . In other words a strict type check is executed so the string representation must be the same. SEE ALSO
array_diff(3), array_udiff(3), array_diff_assoc(3), array_diff_uassoc(3), array_udiff_assoc(3), array_udiff_uassoc(3), array_diff_key(3), array_diff_ukey(3), array_intersect(3), array_intersect_assoc(3), array_intersect_uassoc(3), array_intersect_ukey(3). PHP Documentation Group ARRAY_INTERSECT_KEY(3)
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