v14i045: patch to ephem, v4.13

[downey at dimed1.UUCP]

Posting-number: Volume 14, Issue 45
Submitted-by: downey at dimed1.UUCP
Archive-name: ephem4.13/patch02

Here is a patch to ephem, my interactive astronomical ephemeris, v4.13.
It is a very simple change to one file, objx.c.  It fixes a problem that
occurs in certain circumstances computing the location of objects specified
via parabolic orbital elements.o

thank you very much.
Elwood Downey
downey at dimed.com

*** objx.13	Thu Aug  2 18:56:52 1990
--- objx.new	Thu Aug  2 18:58:54 1990
***************
*** 241,248
  
  	    sll = sin(ll);
  	    cll = cos(ll);
! 	    *lam = atan(rsn*sll/(rpd-rsn*cll))+lpd;
! 	    /* *lam = atan(-1*rpd*sll/(rsn-rpd*cll))+lg+PI; */
  	    range (lam, 2*PI);
  	    *bet = atan(rpd*spsi*sin(*lam-lpd)/(cpsi*rsn*sll));
  

--- 241,250 -----
  
  	    sll = sin(ll);
  	    cll = cos(ll);
! 	    if (rpd < rsn)
! 		*lam = atan(-1*rpd*sll/(rsn-rpd*cll))+lg+PI;
! 	    else
! 		*lam = atan(rsn*sll/(rpd-rsn*cll))+lpd;
  	    range (lam, 2*PI);
  	    *bet = atan(rpd*spsi*sin(*lam-lpd)/(cpsi*rsn*sll));