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Viewing changes to src/nad_cvt.c

  • Committer: Bazaar Package Importer
  • Author(s): Peter S Galbraith
  • Date: 2004-11-06 19:44:53 UTC
  • mto: This revision was merged to the branch mainline in revision 3.
  • Revision ID: james.westby@ubuntu.com-20041106194453-axnsmkh1zplal8mz
Tags: upstream-4.4.9
Import upstream version 4.4.9

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src/nad_cvt.c
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        tb = in;
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        tb.lam -= ct->ll.lam;
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        tb.phi -= ct->ll.phi;
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        tb.lam = adjlon(tb.lam);
 
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        tb.lam = adjlon(tb.lam - PI) + PI;
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        t = nad_intr(tb, ct);
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        if (inverse) {
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                LP del, dif;
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                do {
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                        del = nad_intr(t, ct);
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                        if (del.lam == HUGE_VAL) return del;
 
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                        /* This case used to return failure, but I have
 
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                           changed it to return the first order approximation
 
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                           of the inverse shift.  This avoids cases where the
 
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                           grid shift *into* this grid came from another grid.
 
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                           While we aren't returning optimally correct results
 
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                           I feel a close result in this case is better than
 
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                           no result.  NFW
 
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                           To demonstrate use -112.5839956 49.4914451 against
 
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                           the NTv2 grid shift file from Canada. */
 
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                        if (del.lam == HUGE_VAL) 
 
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                        {
 
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                            if( getenv( "PROJ_DEBUG" ) != NULL )
 
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                                fprintf( stderr, 
 
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                                         "Inverse grid shift iteration failed, presumably at grid edge.\n"
 
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                                         "Using first approximation.\n" );
 
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                            /* return del */;
 
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                            break;
 
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                        }
 
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                        t.lam -= dif.lam = t.lam - del.lam - tb.lam;
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                        t.phi -= dif.phi = t.phi + del.phi - tb.phi;
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                } while (i-- && fabs(dif.lam) > TOL && fabs(dif.phi) > TOL);
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                if (i < 0) {
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                        t.lam = t.phi = HUGE_VAL;
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                        return t;
 
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                    if( getenv( "PROJ_DEBUG" ) != NULL )
 
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                        fprintf( stderr, 
 
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                                 "Inverse grid shift iterator failed to converge.\n" );
 
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                    t.lam = t.phi = HUGE_VAL;
 
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                    return t;
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                }
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                in.lam = adjlon(t.lam + ct->ll.lam);
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                in.phi = t.phi + ct->ll.phi;