Thanks it's good.
I had never used the Karel but with the documentation it is quite simple.
No problem for Roboguide I have it.
The solution was quite simple.
Only particularity: The point transposed in the user frame takes the configuration of the user frame and not of the Point in the world.
After the conversion, I therefore copied the configuration of the "World" point into that of the "User Frame" point.
For those interested, here is my code Karel (Sorry comment in French):
QuoteDisplay MorePROGRAM K_ConvertPtFrame
VAR
NumRUF, NumPrWorld, NumPrUF in CMOS:INTEGER
NumUF : INTEGER
status :INTEGER
UF,PosWorld,PosUF: POSITION
PointWorldToUF1 : POSITION
Real_GET_REG :REAL
flag : BOOLEAN
BEGIN
--Recuperation du numero du repere utilisateur dans le R[NumRUF]
GET_REG(NumRUF,flag,NumUF,Real_GET_REG, status)
--Conversion du Pt world dans UF[NumUF] sur le flag[NumFlag]
--Récuperation du PR
PosWorld = GET_POS_REG(NumPrWorld,status)
--Lecture de UF[NumUF]
UF = $MNUFRAME[1,NumUF]
--Conversion : PosUF = Inv(UF) : PosWorld
PosUF = INV(UF) : PosWorld
--Copie de la configuration
PosUF.CONFIG_data = PosWorld.CONFIG_data
--Ecriture du résultat dans le PR[NumPrUF]
SET_POS_REG(NumPrUF,PosUF,status)
END K_ConvertPtFrame