mandelbrot-inspired-spaceship.sql
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Authored by dereckson on Feb 24 2020, 07:42.

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	F875330: raw.txt
	Feb 24 2020, 07:42

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	WITH RECURSIVE
	-- Grid of points for which the Mandelbrot set will be approximated
	xaxis(x) as (VALUES(-2.0) UNION ALL SELECT x+0.05 FROM xaxis WHERE x < 1.2),
	yaxis(y) as (VALUES(-1.0) UNION ALL SELECT y+0.10 FROM yaxis WHERE y < 1.0),

	-- Mandelbrot iterations
	m(iter, cx, cy, x, y) AS (
	SELECT 0, x, y, 0.0, 0.0 FROM xaxis, yaxis
	UNION ALL
	SELECT iter + 1, cx, cy, xx - yy + cx, xy(x+y) + cy FROM m
	WHERE (xx + yy) < 4.0 AND iter < 28

	),

	m2(iter, cx, cy) AS (
	SELECT max(iter), cx, cy FROM m GROUP BY cx, cy
	),

	-- ASCII representation line per line
	a(t) AS (
	SELECT group_concat(substr(' .+*#', 1 + min(iter/7, 4), 1), '')
	FROM m2 GROUP BY cy
	)

	-- All lines
	SELECT group_concat(rtrim(t), x'0a') FROM a;

dereckson changed the title of this paste from untitled to mandelbrot-inspired-spaceship.sql.

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