WORDPRESS: LIMIT POSTS NUMBER IN ARCHIVE PAGE

gistfile1

/**
 * set the limit number of posts in archive page
 * @return none 
 */
function limit_posts_per_archive_page() {
  if ( is_date() )
    $limit = 10;
  elseif ( is_search() )
    $limit = 10;
  else
    $limit = get_option('posts_per_page');

  set_query_var('posts_per_archive_page', $limit);
}
add_filter('pre_get_posts', 'limit_posts_per_archive_page');