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Mandelbrot plot in postgres
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| WITH RECURSIVE | |
| x(i) AS ( VALUES (0) | |
| UNION ALL SELECT i + 1 | |
| FROM x | |
| WHERE 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, | |
| i | |
| FROM x) AS xgen(x, ix) CROSS JOIN | |
| (SELECT | |
| -1.5 + 0.031 * i, | |
| i | |
| FROM x) 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 < 16.0 | |
| AND I < 27), | |
| Zt (Ix, Iy, I) AS ( | |
| SELECT | |
| Ix, | |
| Iy, | |
| MAX(I) AS I | |
| FROM Z | |
| GROUP BY Iy, Ix | |
| ORDER BY Iy, Ix | |
| ) | |
| SELECT array_to_string( | |
| array_agg(SUBSTRING( | |
| ' .,,,-----++++%%%%@@@@#### ', GREATEST(I, 1), | |
| 1 | |
| )), '' | |
| ) | |
| FROM Zt | |
| GROUP BY Iy | |
| ORDER BY Iy; |
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