[Proj] bug in PJ_tmerc.c ?
Gerald Evenden
gerald.evenden at verizon.net
Wed Jun 1 17:02:55 EDT 2005
For quick fix see below. The test line does not belong there at all
since the
correction for lat_0 offset is done two lines earlier. I will do more
elaborate
tests later.
What took me a minute to figure things out was your specifying both
+a and +b which caused me to assume you were doing an ellipsoid
which does not seem to have this problem. +R= makes things clearer.
:-)
Yes, your code below shows spherical forms but sometimes I do not
read too good. :-(
On Jun 1, 2005, at 9:19 AM, john star wrote:
>
> Hi,
>
> I think that if lat < 0, then there is a bug in PJ_tmerc.c:
> INVERSE(s_inverse); /* sphere */
> double h, g;
>
> h = exp(xy.x / aks0);
> g = .5 * (h - 1. / h);
> h = cos(P->phi0 + xy.y / aks0);
> lp.phi = asin(sqrt((1. - h * h) / (1. + g * g)));
> // if ((xy.y + P->phi0) < 0.) lp.phi = -lp.phi; /* instead of if
> ((xy.y) < 0.) lp.phi = -lp.phi;*/ <-------
> lp.lam = (g || h) ? atan2(g, h) : 0.;
> return (lp);
> }
_____________________________________
Jerry and the low riders: Daisy Mae and Joshua.
"The whole religious complexion of the modern world is due to the
absence from Jerusalem of a lunatic asylum." Havelock Ellis, 1914
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