# The source code of a procedure that generates fractals

Skočit na navigaci Skočit na vyhledávání
```DELIMITER //

CREATE SCHEMA fractal //
USE fractal //

CREATE TABLE disp (
id INT PRIMARY KEY,
content VARCHAR(1000)
) //

id INT PRIMARY KEY,
value INT
) //

INSERT INTO shade (id,value) VALUES (0,ORD('')),(1,ORD('.')),(2,ORD(',')),(3,ORD('-')),
(4,ORD('~')),(5,ORD('*')),(6,ORD(':')),(7,ORD(';')),
(8,ORD('+')),(9,ORD('o')),(10,ORD('O')),(11,ORD('&')),
(12,ORD('%')),(13,ORD('@')) //

CREATE PROCEDURE mandelbrot (IN x_max INT, IN y_max INT)
BEGIN
DECLARE x INT DEFAULT 0;
DECLARE y INT DEFAULT 0;
DECLARE xf0 FLOAT;
DECLARE yf0 FLOAT;
DECLARE xf1 FLOAT;
DECLARE yf1 FLOAT;
DECLARE tf FLOAT;
DECLARE l INT;
DECLARE l_max INT;
DECLARE buffer VARCHAR(1000);
DECLARE tint INT;
TRUNCATE disp;
SELECT MAX(id) INTO l_max FROM shade LIMIT 1;
WHILE y<y_max DO
SET buffer='';
SET x=0;
WHILE x<x_max DO
SET xf0=x*4.0/x_max-2.0;
SET yf0=y*4.0/y_max-2.0;
SET xf1=xf0;
SET yf1=yf0;
SET l=0;
WHILE l<l_max AND xf1*xf1+yf1*yf1<4.0 DO
SET tf=xf1*xf1-yf1*yf1+xf0;
SET yf1=2.0*xf1*yf1+yf0;
SET xf1=tf;
SET l=l+1;
END WHILE;
SELECT value INTO tint FROM shade WHERE id=l;
SET buffer=CONCAT(CHAR(tint),buffer);
SET x=x+1;
END WHILE;
INSERT INTO disp (id,content) VALUES (y,buffer);
SET y=y+1;
END WHILE;
SELECT content FROM disp ORDER BY id ASC;
END //

CALL mandelbrot (50,20) //
```