From 7ef8a7379f7f7d09e71ccae2a0b688c3cd80423f Mon Sep 17 00:00:00 2001
From: Jakob Kaivo <jkk@ung.org>
Date: Fri, 8 Feb 2019 18:42:39 -0500
Subject: merge sources into single tree

---
 src/math/atan2.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 src/math/atan2.c

(limited to 'src/math/atan2.c')

diff --git a/src/math/atan2.c b/src/math/atan2.c
new file mode 100644
index 00000000..be5b9dd6
--- /dev/null
+++ b/src/math/atan2.c
@@ -0,0 +1,41 @@
+# define TGSOURCE "atan2.c"
+#include <math.h>
+#include "nonstd/tgmath.h"
+#include "errno.h"
+#include "nonstd/assert.h"
+
+/** arc tangent **/
+TYPE TGFN(atan2)(TYPE y, TYPE x)
+{
+	ASSERT_NONZERO(x);
+
+	if (y == 0 && x == 0) {
+		errno = EDOM; /* ARGUMENT(y) and ARGUMENT(x) are both LITERAL(0)) */
+		return TGHUGE;
+	}
+
+	if (0) {
+		errno = ERANGE; /* The result cannot be represented */
+		/* RETURN_FAILURE(CONSTANT(HUGE_VAL), A range error occurred); */
+		return TGHUGE;
+	}
+
+	TYPE ret = TGFN(tan)(y / x);
+	/* FIXME: quadrant */
+	/* RETURN_SUCCESS(a value in range `[-PI(), +PI()]'); */
+	return ret;
+}
+
+/***
+functions compute the principal value of the arc tangent of
+ARGUMENT(y)/ARGUMENT(x), using the signs of both to place the return value in
+the correct quadrant.
+***/
+
+/*
+IMPLEMENTATION(The value returned on a domain error, CONSTANT(HUGE_VAL))
+LINK(m)
+*/
+/*
+STDC(1)
+*/
-- 
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