Page Navigation within Wordpress WP_Query

functions.php

<?php

function page_navi_in_query($query) {
  $bignum = 999999999;
  if ( $query->max_num_pages <= 1 )
    return;
  echo '<nav class="pagination">';
  echo paginate_links( array(
    'base'         => str_replace( $bignum, '%#%', esc_url( get_pagenum_link($bignum) ) ),
    'format'       => '',
    'current'      => max( 1, get_query_var('paged') ),
    'total'        => $query->max_num_pages,
    'prev_text'    => '&larr;',
    'next_text'    => '&rarr;',
    'type'         => 'list',
    'end_size'     => 3,
    'mid_size'     => 3
  ) );
  echo '</nav>';
} /* end page navi */

?>