REM ***** MAD TEDDY'S MANDELBROT SET SERIES: REGION #24 *****

REM x limits: -2.00005, -1.666717
REM y limits: -.125, .125

SCREEN 12

iterationlimit = 100

ylow = -1.25 / 10
yhigh = 1.25 / 10
xlow = -2.00005
xhigh = xlow + (yhigh - ylow) * 4 / 3

FOR i = 0 TO 479
    FOR j = 0 TO 639
        x = xlow + j * (xhigh - xlow) / 639
        y = ylow + i * (yhigh - ylow) / 479
        xc = x: yc = y
        iterations = 0
        rsquared = 0
        DO UNTIL rsquared >= 4 OR iterations > iterationlimit
            u = x * x - y * y + xc
            v = 2 * x * y + yc
            rsquared = u * u + v * v
            x = u: y = v
            iterations = iterations + 1
        LOOP
        IF rsquared >= 4 THEN
            IF iterations > 100 THEN
                colour = 0
            ELSE
                colour = 1 + iterations MOD 15
            END IF
        ELSE
            colour = 0
        END IF
        PSET (j, i), colour
    NEXT j
NEXT i

a$ = ""
DO: a$ = INKEY$: LOOP UNTIL a$ = CHR$(27)