$y=((\operatorname{mod}(\operatorname{floor}(\pi*(10^{\operatorname{floor}(x)})),10)-\operatorname{mod}(\operatorname{floor}(\pi*(10^{\operatorname{floor}(x+1)})),10))/(\operatorname{floor}(x)-\operatorname{floor}(x+1)))*x+((\operatorname{floor}(x)*\operatorname{mod}(\operatorname{floor}(\pi*(10^{\operatorname{floor}(x+1)})),10)-\operatorname{floor}(x+1)*\operatorname{mod}(\operatorname{floor}(\pi*(10^{\operatorname{floor}(x)})),10))/(\operatorname{floor}(x)-\operatorname{floor}(x+1)))\ \left\{x\ge0\right\}$

圆周率

y=((\operatorname{mod}(\operatorname{floor}(\pi*(10^{\operatorname{floor}(x)})),10)-\operatorname{mod}(\operatorname{floor}(\pi*(10^{\operatorname{floor}(x+1)})),10))/(\operatorname{floor}(x)-\operatorname{floor}(x+1)))*x+((\operatorname{floor}(x)*\operatorname{mod}(\operatorname{floor}(\pi*(10^{\operatorname{floor}(x+1)})),10)-\operatorname{floor}(x+1)*\operatorname{mod}(\operatorname{floor}(\pi*(10^{\operatorname{floor}(x)})),10))/(\operatorname{floor}(x)-\operatorname{floor}(x+1)))\ \left\{x\ge0\right\}

万能

y=((\operatorname{mod}(\operatorname{floor}(a*(10^{\operatorname{floor}(x)})),10)-\operatorname{mod}(\operatorname{floor}(a*(10^{\operatorname{floor}(x+1)})),10))/(\operatorname{floor}(x)-\operatorname{floor}(x+1)))*x+(\operatorname{floor}(x+1)*\operatorname{mod}(\operatorname{floor}(a*(10^{\operatorname{floor}(x)})),10)-\operatorname{floor}(x)*\operatorname{mod}(\operatorname{floor}(a*(10^{\operatorname{floor}(x+1)})),10))\ \left\{x\ge0\right\}