Math_interpreter

Math interpreter for RPN mathematical notation (revers polish notation)  written in java.
Commands examples in console:
d = 4 6 + 2 *   #20, d is 20
c               #variable not defined
c = 4 1 -       #3,  c is 3
c = 4 -         #error
c               #3,  c is 3
c = 24          #24  c is 24
e = 0           #0,  e is 0
c = e 3 + d 2 * + 5 + c -  #
c
d c e + +
215
addddd = 215


#-means comments in this interpreter and after comments predicted value of operation