c7={0.00106⁢…,0<t<1,0.00139⁢…,-1<t<0⁢ or ⁢1<t<2,0.00321⁢…,-2<t<-1⁢ or ⁢2<t<3,0.0158⁢…,-3<t<-2⁢ or ⁢3<t<4.