Trouble by trying to convert date

Hello,

First I'm a beginner so please be lenient.

Well I'm trying to convert date in order to get the yesterday using the regionnal env of my computer ( I'm French )

So I'm able to do that :

get–date –UFormat %A

And getting correctly "Jeudi" ( Thursday )

I'm able to do that :

(get-date).adddays(-1).dayofweek

And I'm getting Wednesday but I need it in French.

So 'Im regarding to do this :

(get-date).adddays(-1).dayofweek -UFormat %A

But without sucess, any idea ?