real procedure BERBEI (r, z); value r, z; real r, z;
     comment This procedure computes ber(z) if r is set equal to
     zero, bei(z) is produced if r equals 1.0;
begin
   real s, k, c, f, t;
   if r = 0 then
     s ≔ 1
   else
     s ≔ (z × z)/4;
   k ≔ s;
   f ≔ z × z;
   f ≔ f × f;
   for c ≔ 2 step 2 until 100 do
      begin
         if s = s + k then
           go to gate;
         t ≔ (c+r) ×(c+r-1);
         k ≔ -0·0625 × k × f/(t × t);
         s ≔ s + k end;
   gate: BERBEI ≔ s
end BERBEI;