COS.DAT - Revision history

Hobbes at 12:39, 23 July 2013

2013-07-23T12:39:25Z

← Older revision		Revision as of 12:39, 23 July 2013
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	* [[Saved Game Files]]		* [[Saved Game Files]]
	[[Category:Game Files]]		[[Category:Game Files]]
			[[Category:Enemy Unknown/UFO Defense]]

Bomb Bloke at 09:47, 26 January 2008

2008-01-26T09:47:51Z

← Older revision		Revision as of 09:47, 26 January 2008
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			[[image:COS.png\|right\|thumb\|200px\|Plotting of COS values.]]
			[[image:SINE.png\|right\|thumb\|200px\|Plotting of SINE values.]]

	<i>Zaimoni</i>: some working notes		<i>Zaimoni</i>: some working notes

Pi Masta: Added category link

2007-02-07T23:47:32Z

Added category link

← Older revision		Revision as of 23:47, 7 February 2007
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	* [[GEODATA]]		* [[GEODATA]]
	* [[Saved Game Files]]		* [[Saved Game Files]]
			[[Category:Game Files]]

Pi Masta: added See Also links to orphaned page

2007-01-29T21:52:44Z

added See Also links to orphaned page

← Older revision		Revision as of 21:52, 29 January 2007
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	The above trigonometric identities extend the brute verification to the whole file. We may tentatively assume that the game uses 2880 units to a circle.		The above trigonometric identities extend the brute verification to the whole file. We may tentatively assume that the game uses 2880 units to a circle.

			==See Also==
			* [[GEODATA]]
			* [[Saved Game Files]]

Zaimoni at 04:30, 21 September 2006

2006-09-21T04:30:58Z

← Older revision		Revision as of 04:30, 21 September 2006
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	These are precomputed cosine values. The complete prime factorization of the file size 5762 is 2·2881.		These are precomputed cosine values. The complete prime factorization of the file size 5762 is 2·2881.

	~~These should be~~ scaled signed 2-byte integers representing floating-point numbers in the range 0 to 1, scaling factor 2<sup>10</sup> i.e. 1024. First and last values are identical, so it is simplest to assume there are 2880 distinct reference values here. The intent appears to be to enumerate a full circle.		The values are represented as scaled signed 2-byte integers representing floating-point numbers in the range 0 to 1, scaling factor 2<sup>10</sup> i.e. 1024. First and last values are identical, so it is simplest to assume there are 2880 distinct reference values here. Brute verification was conducted by Python script for all angles, that are a multiple of 1/8th of a degree, from 0° to 45° inclusive...exact match.

			The intent appears to be to enumerate a full circle.

	SIN.DAT is the same format, but holds precomputed sine values.		SIN.DAT is the same format, but holds precomputed sine values.
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	* cosine even function, sin odd function identities		* cosine even function, sin odd function identities

	~~Furthermore,~~ the ~~expected nonmonotonic increasing (sine) and nonmonotonic decreasing (cosine) behavior is seen in~~ the ~~raw index range 0~~.~~.720.~~		The above trigonometric identities extend the brute verification to the whole file. We may tentatively assume that the game uses 2880 units to a circle.

	~~This suggests, but does not allow inducting,~~ that the ~~indexing scheme actually is eighths of~~ a ~~degree.~~

	~~Whether the Pythagorean identity is approximated correctly has not been verified yet~~.

Zaimoni at 13:05, 20 September 2006

2006-09-20T13:05:46Z

New page

<i>Zaimoni</i>: some working notes

These are precomputed cosine values. The complete prime factorization of the file size 5762 is 2·2881.

These should be scaled signed 2-byte integers representing floating-point numbers in the range 0 to 1, scaling factor 2<sup>10</sup> i.e. 1024. First and last values are identical, so it is simplest to assume there are 2880 distinct reference values here. The intent appears to be to enumerate a full circle.

SIN.DAT is the same format, but holds precomputed sine values.

The following trigonometric identities are satisfied exactly when the period is taken to be 2880, and the indexing units are taken to be eighths of a degree (observe that 2880=360·8):
* half-circle identity
* supplementary function identity
* cofunction identity
* cosine even function, sin odd function identities

Furthermore, the expected nonmonotonic increasing (sine) and nonmonotonic decreasing (cosine) behavior is seen in the raw index range 0..720.

This suggests, but does not allow inducting, that the indexing scheme actually is eighths of a degree.

Whether the Pythagorean identity is approximated correctly has not been verified yet.