Script calculation based on previous values

[antonopn]

Hi everyone, 

I am facing a problem with a table I am reading. Table has some average weight ranges, but has only "From" values as below. I would like to calculate "To" column inside the script. Columns "TableID" and SizeID are also coming from the table and I need them.

TableID	From	To	SizeID	Calcuation Notes
{3D643767}	900	99999	4	TableID Start -> static value 99999
{3D643767}	900	99999	5	TableID Start -> static value 99999
{3D643767}	900	99999	6	TableID Start -> static value 99999
{3D643767}	800	899,999	4	From changes, has to be (previous(From)-0.001)
{3D643767}	800	899,999	5	From remains, Previous(To)
{3D643767}	800	899,999	6	From remains, Previous(To)
{3D643767}	700	799,999	3	From changes, has to be (previous(From)-0.001)
{3D643767}	700	799,999	4	From remains, Previous(To)
{3D643767}	700	799,999	5	From remains, Previous(To)
{3D643767}	700	799,999	6	From remains, Previous(To)
{3D643767}	600	699,999	2	From changes, has to be (previous(From)-0.001)
{3D643767}	600	699,999	3	From remains, Previous(To)
{3D643767}	600	699,999	4	From remains, Previous(To)
{3D643767}	600	699,999	5	From remains, Previous(To)
{89454FAA}	1200	99999	4	TableID Start -> static value 99999
{89454FAA}	1200	99999	5	TableID Start -> static value 99999
{89454FAA}	1200	99999	6	TableID Start -> static value 99999
{89454FAA}	800	1199,999	4	From changes, has to be (previous(From)-0.001)
{89454FAA}	800	1199,999	5	From remains, Previous(To)
{89454FAA}	800	1199,999	6	From remains, Previous(To)
{89454FAA}	700	799,999	3	From changes, has to be (previous(From)-0.001)
{89454FAA}	700	799,999	4	From remains, Previous(To)
{89454FAA}	700	799,999	5	From remains, Previous(To)
{89454FAA}	700	799,999	6	From remains, Previous(To)

I tried some combinations of "if"  with "previous" but did not work. Could someone please help? 

Thank you in advance for devoting  your time

QlikView 

[MarcoWedel · Accepted solution]

maybe like this?

table1:
LOAD TableID, 
     From, 
     If(TableID=Previous(TableID),If(From=Previous(From),Peek(To),Previous(From)-0.001),99999) as To, 
     SizeID
FROM [https://community.qlik.com/t5/QlikView-App-Dev/Script-calculation-based-on-previous-values/td-p/1901845] (html, codepage is 1252, embedded labels, table is @1);

[antonopn]

@MarcoWedel  you are great. I learned the function 'Peek'. Many thanks!