mandelbrot-example.sql

-- See Nauany's full blog post at https://blog.bitovi.com
WITHRECURSIVEx(i)
AS (
  VALUES(0)
  UNIONALLSELECT i + 1FROM xWHERE i < 101
),
Z(Ix, Iy, Cx, Cy, X, Y, I)
AS (
  SELECT Ix, Iy, X::float, Y::float, X::float, Y::float, 0
  FROM(SELECT -2.2 + 0.031 * i, iFROM x)AS xgen(x,ix)
  CROSSJOIN(SELECT -1.5 + 0.031 * i, iFROM x)AS ygen(y,iy)
  UNIONALLSELECT Ix, Iy, Cx, Cy, X * X - Y * Y + CxAS X, Y * X * 2 + Cy, I + 1
  FROM Z
  WHERE X * X + Y * Y < 16.0
  AND I < 27
),
Zt (Ix, Iy, I)AS (
  SELECT Ix, Iy,MAX(I)AS I
  FROM Z
  GROUPBY Iy, Ix
  ORDERBY Iy, Ix
)
SELECT array_to_string(
  array_agg(
    SUBSTRING(
      ' .,,,-----++++%%%%@@@@#### ',
      GREATEST(I,1),
      1
    )
  ),''
)
FROM Zt
GROUPBY Iy
ORDERBY Iy;