%begin
  %external %real %fn %spec sqrt %alias "sqrtf" (%real n)  {should be in prims. Using Linux/C's external here.}

  %routine TPK(%real %array %name a, b)
    ! given 11 input values a(0),...,a(10), this routine
    ! produces 22 output values b(0),...b(21), according
    ! to the classical TPK algorithm
    %real %fn f(%real t)
      %result = sqrt(|t|) + 5 * t^3
    %end
    %real y
    %integer i
    %cycle i = 10, -1, 0
      y = f(a(i))
      y = 999 %if y > 400
      b(20-2*i) = i
      b(21-2*i) = y
    %repeat
  %end; ! TPK

  %real %array a(0:10), b(0:21)

  TPK(a,b)

%endofprogram