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Forum Index : Microcontroller and PC projects : CMM2 :mandlebrot CSUB

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daveculp
Newbie

Joined: 02/07/2020
Location: United States
Posts: 22

Posted: 05:13pm 08 Jul 2020

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Volhout said
Ported to BBC V basic running on the raspberry Pi zero.

MODE 28

w = 800
h = 600
maxi = 64

TIME = 0
FOR py = 0 TO (h/2 - 1)
�sy = (py / h) * 2 - 1
�FOR px = 0 TO w - 1
� �sx = (px / w) * 3.5 - 2.5
� �i = 0
� �x = 0
� �y = 0
� �WHILE ((x^2 + y^2 < 4) AND (i < maxi))
� � �xt = x^2 - y^2 + sx
� � �y = 2 * x * y + sy
� � �x = xt
� � �i = i + 1
� �ENDWHILE
� �GCOL i/maxi * 64
� �POINT px, py
� �POINT px, h-py
�NEXT px
NEXT py
PRINT TIME*10

run time : 16 seconds (10x slower than the CMM2 CSUB)

I forgot about the optimization of mirroring the horizontal axis! That sped it up by twice.

I got 38 seconds on the CMM2 pure BASIC with that optimization and 100 iterations.

Sasquatch

Guru

Joined: 08/05/2020
Location: United States
Posts: 376

Posted: 09:10pm 08 Jul 2020

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daveculp said

I forgot about the optimization of mirroring the horizontal axis! �That sped it up by twice.

I got 38 seconds on the CMM2 pure BASIC with that optimization and 100 iterations.

The CSub currently doesn't use that optimization. It could be implemented for the special case of YCenter = 0.0 It would likely double the size of the code to double the speed for that one special case.

-Carl

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