var a = 1, temperatures = [5, 6, 7, 8, 9, 10, 12, 14, 16, 20, 20], time = 0, h = 5, tau = 1, curr, prev, next, counter;
document.getElementById("start").onclick = function() {
        a = Number(document.getElementById('kf').value);
        if (isNaN(a))
                a = 1;
            if (a > 5)
                a = 5;
            temperatures[10] = Number(document.getElementById('out').value);
        if (isNaN(temperatures[10]))
            temperatures[10] = 20;
        temperatures[0] = Number(document.getElementById('seg1').value);
        if (isNaN(temperatures[0]))
            temperatures[0] = 5;
        temperatures[1] = Number(document.getElementById('seg2').value);
        if (isNaN(temperatures[1]))
            temperatures[1] = 6;
        temperatures[2] = Number(document.getElementById('seg3').value);
        if (isNaN(temperatures[2]))
            temperatures[2] = 7;
        temperatures[3] = Number(document.getElementById('seg4').value);
        if (isNaN(temperatures[3]))
            temperatures[3] = 8;
        temperatures[4] = Number(document.getElementById('seg5').value);
        if (isNaN(temperatures[4]))
            atemperatures[4] = 9;
        temperatures[5] = Number(document.getElementById('seg6').value);
        if (isNaN(temperatures[5]))
            temperatures[5] = 10;
        temperatures[6] = Number(document.getElementById('seg7').value);
        if (isNaN(temperatures[6]))
            temperatures[6] = 12;
        temperatures[7] = Number(document.getElementById('seg8').value);
        if (isNaN(temperatures[7]))
            temperatures[7] = 14;
        temperatures[8] = Number(document.getElementById('seg9').value);
        if (isNaN(temperatures[8]))
            temperatures[8] = 16;
        temperatures[9] = Number(document.getElementById('seg10').value);
        if (isNaN(temperatures[9]))
            temperatures[9] = 20;
        document.getElementById("enter-data").style = "display: none";
        document.getElementById("main-block").style = "display: block";
        document.getElementById("time-block").style = "display: block";
        a = 2;
        temperatures[0] = 400;
        temperatures[1] = 25;
        temperatures[2] = 800;
        temperatures[3] = 600;
        temperatures[4] = 200;
        temperatures[5] = 100;
        temperatures[6] = 500;
        temperatures[7] = 400;
        temperatures[8] = 300;
        temperatures[9] = 200;
        temperatures[10] = 25;
        calculate();
};

function calculate() {
    for (let i = 0; i < 10; i++) {
        curr = temperatures[i];
        if (temperatures[i-1] != null)
            prev = temperatures[i-1];
        else
            prev = temperatures[i];
        if (typeof temperatures[i+1] != null)
            next = temperatures[i+1];
        else
            next = temperatures[i];
        temperatures[i] = curr + (a**2 * tau/h**2) * (prev - 2 * curr + next);
    }
    document.getElementById("el1").innerHTML = temperatures[0].toFixed(2);
    document.getElementById("el2").innerHTML = temperatures[1].toFixed(2);
    document.getElementById("el3").innerHTML = temperatures[2].toFixed(2);
    document.getElementById("el4").innerHTML = temperatures[3].toFixed(2);
    document.getElementById("el5").innerHTML = temperatures[4].toFixed(2);
    document.getElementById("el6").innerHTML = temperatures[5].toFixed(2);
    document.getElementById("el7").innerHTML = temperatures[6].toFixed(2);
    document.getElementById("el8").innerHTML = temperatures[7].toFixed(2);
    document.getElementById("el9").innerHTML = temperatures[8].toFixed(2);
    document.getElementById("el10").innerHTML = temperatures[9].toFixed(2);
    time++;
    document.getElementById("time").innerHTML = time;
    counter = 0;
    for (let i = 0; i < 10; i++)
        for (let j = 1; j < 10; j++)
            if ((Math.abs(temperatures[i]) - Math.abs(temperatures[j-1])) < 0.5)
                counter++;
        if (counter == 90) {
            document.getElementById("time").style = "color: red";
            document.getElementById("end").style = "display: block";
            return;
        }
    setTimeout(calculate, 1);
}