Bash - Matrix multiplication, passing associative arrays to functions, returning associative arrays from functions

linalg.sh

#!/bin/bash -eu

function linalg_matrix_dump {
    local -n M=${1}
    local -a data=(${M[data]})
    typeset -i rows=${M[rows]}
    typeset -i cols=${M[cols]}
    typeset -i i j
    printf "%s:\n" ${1}
    for ((i=0;i<rows;i++)) ; do
        printf '    | '
        for ((j=0;j<cols;j++)) ; do
            idx=$((i*cols+j))
            printf "%s " ${data[$((i*cols+j))]}
        done
        printf '\n';
    done
    printf '\n';
}

function linalg_matrix_multiply {
    local -n A=${1}
    local -n B=${2}
    local -a dataA=(${A[data]})
    local -a dataB=(${B[data]})
    typeset -i rowsA=${A[rows]}
    typeset -i colsA=${A[cols]}
    typeset -i rowsB=${B[rows]}
    typeset -i colsB=${B[cols]}
    [[ $((rowsA*colsA)) -eq ${#dataA[@]} ]] || return 1
    [[ $((rowsB*colsB)) -eq ${#dataB[@]} ]] || return 1
    [[ ${colsA} -eq ${rowsB} ]] || return 1
    typeset -i i j k a b c
    local -a dataC
    for ((i=0;i<rowsA;i++)) ;do
        for ((j=0;j<colsB;j++)) ;do
            local sum=0
            for ((k=0;k<rowsB;k++)) ;do
                local a=$((i*colsA+k))
                local b=$((j+colsB*k))
                local cellA=${dataA[a]}
                local cellB=${dataB[b]}
                sum=$(echo "${sum} + ${cellA} * ${cellB}" | bc -ls)
            done
            local c=$((i*colsB+j))
            dataC[$c]=${sum}
        done
    done
    declare -A result=([rows]=${rowsA} [cols]=${colsB} [data]=${dataC[@]})
    declare -p result
}



declare -A m1=([rows]=2 [cols]=2 [data]="1 2 3 4")
linalg_matrix_dump m1

declare -A m2=([rows]=2 [cols]=3 [data]="0 1 2 1 2 3")
linalg_matrix_dump m2

m=$(linalg_matrix_multiply m1 m2)
eval "${m/result=/m=}"
linalg_matrix_dump m