When you initialise an R variable that value is assigned to the floating point store. When you assign a value to a save point variable the actual floating point value stored in CMES is the machine co-ordinate value relative to the reset sphere. There is a loss of precision due to innaccuracies of floating point notation (a common programming problem).
Do the following
RE\Y\Y !No transform will take place.
GP\0\0\0\SP,1
X1=0.769
R1=0.769
Now your calculation will yield zero.
Duncan.