[0], temp_eq[1], temp_eq[2]);
        context.moveTo(x_to_client(xys[0][0]), y_to_client(xys[0][1]));
        context.lineTo(x_to_client(xys[1][0]), y_to_client(xys[1][1]));
        context.strokeStyle = line_colors[closest_eq_id - 1];
        context.setLineDash([4, 4]);
        context.stroke();
        context.setLineDash([]);
        context.closePath();
    }
}



//////
/// equations and matrix
function printable(a) {
    a_trimmed = Number(a.toFixed(2));
    if (Number.isInteger(a_trimmed))
        r