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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Flat Bygrave alternative configuration
From: Robin Stuart
Date: 2014 Jun 29, 04:13 -0700
Hanno,
As promised I attach pdf files in which the cosine scales are printed high and low on the page. The programs that generated them differ by a single statement
/CosScaleStartPoint { 2.3 cm 11.5 cm } def
for the upper scale and
/CosScaleStartPoint { 2.3 cm 1.5 cm } def
for the lower. They can be printed together by passing the page twice but as noted previously they will not then be precisely aligned.
I also attach a version of the flat Bygrave in which the cosine scale runs from -89°15' through zero to 89°15' with signs omitted on the negative angles. This extended scale makes it fairly obvious why the dual zero pointers work. As I alluded to in an earlier post, with this scale multiplication is performed by aligning a zero pointer with a number on the cotangent scale and reading left to right. Division is performed by aligning a zero pointer with a number on the cotangent scale and reading right to left. The CosScaleTicksDown flag has been set to true in this scale which allows calculations to be performed by aligning the cosine and cotangent scales baseline to baseline which may enhance visibility.
The code to generate the scales requires explicitly listing how each and every scale tick is drawn and labeled. Inreasing the number of ticks just requires expanding that list. Where do you think the additional ticks should be added?
Regards,
Robin
Note: in generating the last scale I found that not all signs were being omitted from the lables of negative angles and also that the program would fail for certain combinations parameters. These bugs have been fixed in the attached Postscript file and I will post the new version of the code for other Bgrave types in due course
From: Robin Stuart
Date: 2014 Jun 29, 04:13 -0700
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