Comment 1 for bug 610738

@Jay....

Hello.

Be carefull, take the price from the picking related to the return packing, not any value from the product.....

I mean:

the behaviour exposed by invitu is the idealsituation and he is right, but in the real world exist a case with several purchases of several products and the return _must_ be done taking in reference exactly _wht packing is being returned.

Taking the same invitu's example and adding this situation

For example :
1- We have 10 products with average price = 100
2- We receive 5 products with price = 80 --> average price is calculated as (10*100+5*80)/(10+5) = 93,33
NEW SITUATION 2.5- We receive 5 products with price = 82 --> average price is calculated as (10*100+5*82)/(15+5) = 90,5
CASE A.
3- We return 3 products from the last packing list (the one where products cost 82)
The new average price should be
(93,33*20 - 3*82)/(20-3)=92
CASE B
3- We return 3 products from the last packing list (the one where products cost 80)
The new average price should be
(93,33*20 - 3*80)/(20-3)=92,35

As you can see is not the same taking as reference one or another...

I attach a spreedsheet that explain this example with this explicit equations are in cells and the verification model of the concepts, _ALWAYS_ the cost calculated by the average price* inventory should be the same that sum all transactions (quantity1*pricetransactios1+quantity2*pricetransactios2+.......)

thanks jay.