bash: integer * float multiplication

I am trying to write a simple multiplication between int and float numbers in bash:

int='10'
float='0.001'

# should give 0.01
multip=$(( float*int ))

produces error

bash: 0.001 : erreur de syntaxe : opérateur arithmétique non valable (le symbole erroné est « .001 »)

what should be fixed ?

>Solution :

Bash doesn’t support floats. Use an external program for that, e.g. bc.

int=10
float=0.001
multip=$(bc <<< "$int * $float")

Note that bc doesn’t output the leading 0 in 0.01, so you need to add some string processing, e.g.

multip=${multip/#./0.} # Insert 0 before the leading dot.