[bash shell] how to calculate float times float

It is noted for myself, please do check for yourself.

#!/bin/bash############################################alpha=0.0for((i=0;i<=10;i++))do    alpha=`echo "scale=2;$i*0.1"|bc`    echo "####################"$i    echo "alpha="$alpha    echo $alpha > input_b21_temp.txt    root -l -q b21_mc_alpha.C < input_b21_temp.txt    mv res_b21.root "./res_b21/"$i".root"    rm input_b21_temp.txtdone###########################################