INCLUDE "D2:REAL.ACT" ;from the Action! Tool Kit

PROC Superellipse(INT x0 BYTE y0 REAL POINTER n BYTE a)
  INT ARRAY f(100)
  REAL ar,xr,tmp1,tmp2,tmp3,one,invn
  INT x

  IntToReal(1,one)
  RealDiv(one,n,invn) ;1/n
  IntToReal(a,ar)
  Power(ar,n,tmp1) ;a^n

  Plot(x0,y0-a)
  FOR x=0 TO a
  DO
    IntToReal(x,xr)
    Power(xr,n,tmp2) ;x^n
    RealSub(tmp1,tmp2,tmp3) ;a^n-x^n
    Power(tmp3,invn,tmp2) ;(a^n-x^n)^(1/n)
    f(x)=RealToInt(tmp2)
    DrawTo(x0+x,y0-f(x))
  OD

  x=a
  WHILE x>=0
  DO
    DrawTo(x0+x,y0+f(x))
    x==-1
  OD

  FOR x=0 TO a
  DO
    DrawTo(x0-x,y0+f(x))
  OD

  x=a
  WHILE x>=0
  DO
    DrawTo(x0-x,y0-f(x))
    x==-1
  OD
RETURN

PROC Main()
  BYTE CH=$02FC,COLOR1=$02C5,COLOR2=$02C6
  REAL n

  Graphics(8+16)
  Color=1
  COLOR1=$0C
  COLOR2=$02

  ValR("2.5",n)
  Superellipse(160,96,n,80)

  DO UNTIL CH#$FF OD
  CH=$FF
RETURN