Matrix Addition, Subtraction and Multiplication

#!/bin/bash
function inputMatrix(){
    echo "For Matrix A:-"
    for (( i=0; i<rowA; i++ ))
    do
        for (( j=0; j<columnA; j++ ))
        do
            echo "Value at [$i][$j] : "
            read MatrixA[$i$j]
        done
    done
    echo "For Matrix B:-"
    for (( i=0; i<rowB; i++ ))
    do
        for (( j=0; j<columnB; j++ ))
        do
            echo "Value at [$i][$j] : "
            read MatrixB[$i$j]
        done
    done
}
function add(){
    for (( i=0; i<rowA; i++ ))
    do
        for (( j=0; j<columnA; j++ ))
        do
            let MatrixC[$i$j]=${MatrixA[$i$j]}+${MatrixB[$i$j]}
        done
    done
}
function sub(){
    for (( i=0; i<rowA; i++ ))
    do
        for (( j=0; j<columnA; j++ ))
        do
            let MatrixC[$i$j]=${MatrixA[$i$j]}-${MatrixB[$i$j]}
        done
    done
}
function mul(){
    for (( i=0; i<rowA; i++ ))
    do
        for (( j=0; j<columnB; j++ ))
        do
            sum=0
            for (( k=0; k<columnA; k++ ))
            do
                sum=`expr "$sum+(${MatrixA[$i$k]} * ${MatrixB[$k$j]})"|bc`
            done
            MatrixC[$i$j]=$sum
        done
    done
}
function displayMatrix(){
    for (( i=0; i<rowA; i++ ))
    do
        for (( j=0; j<columnB; j++ ))
        do
            echo -n ${MatrixC[$i$j]}" "
        done
        echo ""
    done
}
rowA=2
columnA=2
rowB=2
columnB=2
inputMatrix
echo -n "1.Add 2. Subtract 3. Multiply: "
read ip
case $ip in
    1):
        add;;
    2):
        sub;;
    3):
        mul;;
esac
displayMatrix