Dysolve Pro

1.) Added summation function &#39;fesum&#39; for summing items for each vector &#39;n&#39; element. It looks like math &#39;Sigma&#39; summation.<br>2.) Added summation function &#39;irsum&#39; for summing items in range of &#39;i&#39; variable.<br>3.) Fixed expression validation issues, when integral function is called within another function.<br>4.) You can pick entities from the worksheet when