error- multiplying negative decimal values

a=10.02
pattern=-11.01
b=$(echo | awk '{ print $a*$pattern}')
echo $b

its not working even
ALso tried `expr $a \* $pattern`

No LUCK

 
b=$(echo | awk '{ print $a*$pattern}')

 
b=$(echo "$a * $pattern" | bc)

bc is not register on my m/c,
any other clue?

$ a=10.02
$ pattern=-11.01
$ echo $pattern + $a | bc
-.99
$ echo $pattern \* $a | bc
-110.33
$

---------- Post updated at 03:17 PM ---------- Previous update was at 03:15 PM ----------

$ echo "10.02 -11.01" | nawk '{b=$1*$2; {print b}}'
-110.32
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