表达式4: "T" left parenthesis, "x" , right parenthesis equals rotate left parenthesis, "x" , token 3 , StartFraction, 360 Over "a" , EndFraction , right parenthesisTx=rotatex,,360a
4
表达式5: "f" left parenthesis, "n" , right parenthesis equals "T" left parenthesis, "f" left parenthesis, "n" minus 1 , right parenthesis , right parenthesisfn=Tfn−1
5
表达式6: "f" left parenthesis, 0 , right parenthesis equals token 7f0=
6
表达式7: "f" left parenthesis, left bracket, 0... "a" minus 1 , right bracket , right parenthesisf0...a−1
