Change number of posts displayed in WordPress blog page by weekdays

gistfile1.txt

function number_of_posts_per_day($query){
    if (date("l")=="Sunday") {
        $query->set('posts_per_page', 20);
    }
    elseif (date("l")=="Monday") {
        $query->set('posts_per_page', 10);
    }
    elseif (date("l")=="Tuesday") {
        $query->set('posts_per_page', 5);
    }

    return $query;
}


add_filter('pre_get_posts', 'number_of_posts_per_day');