The purpose of this task is to explore working with   complex numbers.



Task

Given   n,   find the   nth   roots of unity.




 
// cleandisp just to display 0 when n < 10^-10 
{def cleandisp
 {lambda {:n}
  {if {<= {abs :n} 1.e-10} then 0 else :n}}}
-> cleandisp
 
{def uroots
 {lambda {:n}
  {S.map {{lambda {:n :i}
                  {let { {:theta {/ {* 2 {PI} :i} :n}}  
                       } {cons {cleandisp {cos :theta}} 
                               {cleandisp {sin :theta}}}}} :n}
         {S.serie 0 {- :n 1}}} }}
-> uroots
 
{S.map {lambda {:i} {hr}i = :i -> {uroots :i}} {S.serie 2 10}}
-> i = 2 -> (1 0) (-1 0) i = 3 -> (1 0) (-0.4999999999999998 0.8660254037844388) (-0.5000000000000004 -0.8660254037844384) 
i = 4 -> (1 0) (0 1) (-1 0) (0 -1) 
i = 5 -> (1 0) (0.30901699437494745 0.9510565162951535) (-0.8090169943749473 0.5877852522924732) (-0.8090169943749475 -0.587785252292473) (0.30901699437494723 -0.9510565162951536) 
i = 6 -> (1 0) (0.5000000000000001 0.8660254037844386) (-0.4999999999999998 0.8660254037844388) (-1 0) (-0.5000000000000004 -0.8660254037844384) (0.5 -0.8660254037844386) 
i = 7 -> (1 0) (0.6234898018587336 0.7818314824680297) (-0.22252093395631434 0.9749279121818236) (-0.900968867902419 0.43388373911755823) (-0.9009688679024191 -0.433883739117558) (-0.2225209339563146 -0.9749279121818235) (0.6234898018587334 -0.7818314824680299) 
i = 8 -> (1 0) (0.7071067811865476 0.7071067811865475) (0 1) (-0.7071067811865475 0.7071067811865476) (-1 0) (-0.7071067811865477 -0.7071067811865475) (0 -1) (0.7071067811865475 -0.7071067811865477) 
i = 9 -> (1 0) (0.7660444431189781 0.6427876096865393) (0.17364817766693041 0.984807753012208) (-0.4999999999999998 0.8660254037844388) (-0.9396926207859083 0.3420201433256689) (-0.9396926207859084 -0.34202014332566866) (-0.5000000000000004 -0.8660254037844384) (0.17364817766692997 -0.9848077530122081) (0.7660444431189779 -0.6427876096865396) 
i = 10 -> (1 0) (0.8090169943749475 0.5877852522924731) (0.30901699437494745 0.9510565162951535) (-0.30901699437494734 0.9510565162951536) (-0.8090169943749473 0.5877852522924732) (-1 0) (-0.8090169943749475 -0.587785252292473) (-0.30901699437494756 -0.9510565162951535) (0.30901699437494723 -0.9510565162951536) (0.8090169943749473 -0.5877852522924732)
 
 