表达式5: "f" left parenthesis, "x" , right parenthesis equals absolute value left parenthesis, StartFraction, 2 left parenthesis, "u" plus StartNestedFraction, pi NestedOver 2 , EndNestedFraction , right parenthesis Over pi , EndFraction , right parenthesis minus 1fx=abs2u+π2π−1
5
... which is used in place of sine to make it jagged:
6
表达式7: "r" equals "f" left parenthesis, theta , right parenthesis plus "f" left parenthesis, 2 theta , right parenthesisr=fθ+f2θ
00
定义域\theta最小值：
less than or equal to theta less than or equal to≤θ≤
2 pi2π
定义域\theta最大值：
7
表达式8: "y" less than "f" left parenthesis, "x" , right parenthesis plus left parenthesis, "f" left parenthesis, 2 "x" , right parenthesis , right parenthesisy<fx+f2x
8
... but Justin's original isn't quite so jagged! So what's in between sin(x) and a triangular wave?
