#!/bin/bash

### hamming.sh
# Convolve input vector with 3-element Hamming window [0.23, 0.54, 0.23]
# note: bash built-in $(( )) constructs only support integer arithmetic
# floating point operation will require another language such as awk, perl, or
# python.

### input vector as array
X=($1)
echo ${#X[@]}

### Hamming window vector
H=(0.23 0.54 0.23)
echo ${#H[@]}

### length of output
L=$(( ${#X[@]} + ${#H[@]} - 1 ))

### iterate over both vectors
for N in $( seq 0 1 $L ) ; do
    for M in $( seq 0 1 $(( ${#H[@]} - 1 )) ) ; do
        if [ $(( $N >= $M )) ] ; then
            printf "N=$N\tM=$M\tN-M=$(( $N - $M ))\n"
        else
            continue
        fi
    done
done