表达式4: "I" left parenthesis, "n" , right parenthesis equals Start integral from 0 to 2 pi , end integral, StartAbsoluteValue, "F" left parenthesis, "n" , "x" , right parenthesis , EndAbsoluteValue "d" "x"In=∫2π0Fn,xdx
4
表达式5: "I" left parenthesis, "N" , right parenthesisIN