TURING Exercise 4.1.7

; Write a TM which computes the function f(x) = 2x, where x is represented in unary notation.

0 1 # r 1R
0 # # r 0
0 _ _ l 4L
1R 1 1 r 1R
1R # # r 1R
1R _ # l 1L
1L # # l 1L
1L 1 1 l 1L
1L _ _ r 0
2R # # r 2R
2R 1 # r 1R
2R _ _ r 3L
3L # # l 3L
3L _ _ r 0
4L # # l 4L
4L _ _ r 4R
4R # 1 r 4R
4R _ _ r halt