Robert Kern wrote: > Fredrik Lundh wrote: >> Terry Reedy wrote: >> >>> This is far more accurate than any measured latitude could be. >> you're saying that we don't measure geographical positions on an atomic >> scale? ;-) >> >> (it's too late for serious calculations, but I'd guess we're talking >> Ångströms here, right?) > > The meter was originally defined to be 1e-7 of the distance between the > equator > and the North pole, so 1 degree of latitude is roughly 1e7 m/90 ~ 1e5 m. > 1e-16 * > 1e5 = 1e-11, 1/10th of an Ångström.
Oops. Most of the latitude values will have 2 digits before the decimal point, so in fact, we need 1e-14 deg * 1e5 m/deg = 1e-9 m or 10 Ångströms. The quoted precision of the actual values that the OP used as examples is about 1e-7 deg * 1e5 m/deg = 1e-2 m. -- Robert Kern "I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco -- http://mail.python.org/mailman/listinfo/python-list
