defmodule EctoPSQLExtras.Mandelbrot do
@behaviour EctoPSQLExtras
def info do
%{
title: "The mandelbrot set",
columns: [
%{name: :art, type: :string}
]
}
end
def query(_args \\ []) do
"""
/* ECTO_PSQL_EXTRAS: The mandelbrot set */
WITH RECURSIVE 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, i from generate_series(0,101) as i) as xgen(x,ix),
(select -1.5 + 0.031 * i, i from generate_series(0,101) as i) as ygen(y,iy)
UNION ALL
SELECT IX, IY, CX, CY, X * X - Y * Y + CX AS X, Y * X * 2 + CY, I + 1
FROM Z
WHERE X * X + Y * Y < 16::float
AND I < 100
)
SELECT array_to_string(array_agg(SUBSTRING(' .,,,-----++++%%%%@@@@#### ', LEAST(GREATEST(I,1),27), 1)),'') AS art
FROM (
SELECT IX, IY, MAX(I) AS I
FROM Z
GROUP BY IY, IX
ORDER BY IY, IX
) AS ZT
GROUP BY IY
ORDER BY IY;
"""
end
end