Combined conditions ( Financial )

Hello ,

this is the first time I post in an excel forum so forgive me if explaining myself can be very modest ,

Im a financial analyst in a bank and I was working on a project using excel lastly and I had some issues completing a task.


I have tree columns , lets suppose these values

A B C ( the result )
-8 5 10

7 -10 -20

-9 -3 -6
I want this condition for C : if last value in B or A is negatif then multiply * 2 the next positif value only for B and stop it if we have tree consecutive negatif values

Wich means in our case : -3 ( A ) is negatif so c must be -3*2= -6 , and next cell is -10 ( B ) so c = -10*2 = -20 and finally we have 5 in B so 5*2 is 10

I just want to make automatic all this processus in C because Im obligated to do it manually while I have a database of thousands of informations.

Thank you
Best regards.