1 files changed, 35 insertions, 0 deletions
diff --git a/src/math/acos.c b/src/math/acos.c
new file mode 100644
index 00000000..a610fe2e
--- /dev/null
+++ b/src/math/acos.c
@@ -0,0 +1,35 @@
+# define TGSOURCE "std/9899-1990/math/acos.c"
+#include <math.h>
+#include "errno.h"
+#include "nonstd/tgmath.h"
+
+/** arc cosine **/
+TYPE TGFN(acos)(TYPE x)
+{
+	if (x < -1 || x > 1) {
+		errno = EDOM;	/* ARGUMENT(x) not in the range [-1, +1] */
+		return TGHUGE;
+	}
+
+	if (0) {
+		errno = ERANGE; /* The result cannot be represented */
+		/* RETURN_FAILURE(CONSTANT(HUGE_VAL), A range error occurred); */
+		return TGHUGE;
+	}
+
+	/* RETURN_SUCCESS(a value in range `[0, PI()]'); */
+	return (TYPE)0.0;
+}
+
+/***
+compute the principal value of the arc cosine of ARGUMENT(x), which must be in
+the range [-1, +1].
+***/
+
+/*
+IMPLEMENTATION(The value returned on a domain error, CONSTANT(HUGE_VAL))
+LINK(m)
+*/
+/*
+STDC(1)
+*/