The following line is not working in my script:
a=$(echo "scale=3;(2*$j/(sqrt(3)*$i))" | bc)
a1=$(echo `expr "scale=3; $a^(1/3)"` | bc -l)
The error it is giving:
Runtime warning (func=(main), adr=21): non-zero scale in exponent
I just want to have the value of cube root of 'a'. Somehow, I am not getting it. Please give some idea.
This line is problematic:
a1=$(echo `expr "scale=3; $a^(1/3)"` | bc -l)
Since you cannot use a non-integer value as a power in bc.
Example to reproduce this error:
bc -l
bc 1.06
sqrt(3)^(1/3)
Runtime warning (func=(main), adr=11): non-zero scale in exponent
1
Solution:
You can use this function to calculate cube root:
a1=$(bc -l <<< "scale=3; e(l($i)/3)")
Example:
i=8; bc -l <<< "scale=3; e(l($i)/3)"
1.999
Or use awk as mentioned by @fedorqui
You probably want to use awk for this instead of using complex bc syntaxs:
awk -v num=$bash_variable 'BEGIN{print num^(1/3)}'
For example:
v=3
awk -v num=$v 'BEGIN{print num^(1/3)}'
Returns: 1.44225.
Or store the variable for a further usage:
var=$(awk -v num=$v 'BEGIN{print num^(1/3)}')