Fix #1074. Fix unit conversion factors for geod. #1075
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Previously, unit conversion using atof(unit_list[i].to_meter) which
gives the wrong answer with, e.g., "1/10". Now it directly uses
unit_list[i].factor (e.g., 0.1).
Also fix all the conversion factors for the US Surveyor units so that
they are the closest doubles. E.g., the conversion factors for US
feet are
factor rel error
old 0.304800609601219 6e-16
12/39.37 1e-16
now 1200/3937.0 5e-17
Maybe someone should check the Indian units (but it's possible that
India and Pakistan have different standards).
|
Thanks! I figured this would be a simple fix. Changing the unit conversion factors seem to break some tests, though. |
|
I know! We'll see... The US-inch was way off, 2 parts in a million. The others are down in the noise. |
Bletch, pj_init also decodes the to_meters field of pj_unit, but only handles plain numbers or 1/nnn, but not 1./nnn or mmm/nnn. (So the original code would have not decoded the us-in entry properly.) Probably pj_init should be changed to use the factor field instead. Alternatively pj_init should look for a "/" anywhere in the field and decode the numerator and denominator as separate doubles. This would be needed if ratios are ever to be entered directly by the user (this is the strategy used by GeographicLib). And then, of course, the functionality should be provided by a separate utility function.
Yes, that would be the logical progression. I added the factor field while introducing the |
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Previously, unit conversion using atof(unit_list[i].to_meter) which
gives the wrong answer with, e.g., "1/10". Now it directly uses
unit_list[i].factor (e.g., 0.1). This fixes #1074.
Also fix all the conversion factors for the US Surveyor units so that
they are the closest doubles. E.g., the conversion factors for US
feet are
Maybe someone should check the Indian units (but it's possible that
India and Pakistan have different standards).