Float Arithmatic in Bash

[vishal.rossi]

Hi,
I have to use this code below which works fine :

output=$path
tmp_dir=$path1
mu=200
sigma=80
output_dir=$output
tmp_dir=$tmp
mu_length=$mu
sigma_length=$sigma
echo "input_format=sam
sv_type=all
mates_orientation=RF
read1_length=100
read2_length=100
output_dir=$output
tmp_dir=$tmp
mu_length=$mu
sigma_length=$sigma
window_size=$((sigma*2 + mu*2))" > abc.txt


What I need to do is
window_size=$((sigma*2.82 + mu*2)) # float multiplication

Will this thing work :
window_size=$(('scale=4; sigma*2.82 + mu*2' | bc))

Or any other way by which I can do float multiplication.

Thanks in advance for the help

[dpryan]

Will this thing work :
window_size=$(('scale=4; sigma*2.82 + mu*2' | bc))

Something like that should work. Bash doesn't do floating point arithmetic by itself. Honestly, you'll find if more convenient to anything more complicated in another language (perl, python, whatever). Shell scripts are great for simple process control jobs, but I wouldn't want to write anything else using them.

[Richard Finney]

Try this
window_size=`echo "sigma*2.82+mu*2" | bc`
echo $window_size

or

window_size=`echo "scale=4;$sigma*2.82+$mu*2" | bc`

See : http://stackoverflow.com/questions/1...-expr-on-float

[vishal.rossi]

Thanks for the reply. I too figured out a way:

window_size=$(echo $d_mu*2 + $e_sigma*2.82 | bc -l)
step_length=$(echo $d_mu*2/4 + $e_sigma*2.82/4 | bc -l)