New

git-svn-id: http://svn.osgeo.org/metacrs/proj/trunk@776 4e78687f-474d-0410-85f9-8d5e500ac6b2

1 files changed, 49 insertions, 0 deletions

diff --git a/src/nad_cvt.c b/src/nad_cvt.c
new file mode 100644
index 00000000..600ea3cd
--- /dev/null
+++ b/src/nad_cvt.c
@@ -0,0 +1,49 @@
+#ifndef lint
+static const char SCCSID[]="@(#)nad_cvt.c	4.3   95/09/23 GIE REL";
+#endif
+#define PJ_LIB__
+#include <projects.h>
+#define MAX_TRY 9
+#define TOL 1e-12
+	LP
+nad_cvt(LP in, int inverse, struct CTABLE *ct) {
+	LP t, tb;
+
+	if (in.lam == HUGE_VAL)
+		return in;
+	/* normalize input to ll origin */
+	tb = in;
+	tb.lam -= ct->ll.lam;
+	tb.phi -= ct->ll.phi;
+	tb.lam = adjlon(tb.lam);
+	t = nad_intr(tb, ct);
+	if (inverse) {
+		LP del, dif;
+		int i = MAX_TRY;
+
+		if (t.lam == HUGE_VAL) return t;
+		t.lam = tb.lam + t.lam;
+		t.phi = tb.phi - t.phi;
+
+		do {
+			del = nad_intr(t, ct);
+			if (del.lam == HUGE_VAL) return del;
+			t.lam -= dif.lam = t.lam - del.lam - tb.lam;
+			t.phi -= dif.phi = t.phi + del.phi - tb.phi;
+		} while (i-- && fabs(dif.lam) > TOL && fabs(dif.phi) > TOL);
+		if (i < 0) {
+			t.lam = t.phi = HUGE_VAL;
+			return t;
+		}
+		in.lam = adjlon(t.lam + ct->ll.lam);
+		in.phi = t.phi + ct->ll.phi;
+	} else {
+		if (t.lam == HUGE_VAL)
+			in = t;
+		else {
+			in.lam -= t.lam;
+			in.phi += t.phi;
+		}
+	}
+	return in;
+}