1 files changed, 34 insertions, 0 deletions
diff --git a/src/math/log.c b/src/math/log.c
new file mode 100644
index 00000000..a75fdafa
--- /dev/null
+++ b/src/math/log.c
@@ -0,0 +1,34 @@
+# define TGSOURCE "log.c"
+#include <math.h>
+#include "nonstd/tgmath.h"
+#include "errno.h"
+
+/** natural logarithm **/
+TYPE TGFN(log)(TYPE x)
+{
+	if (x < 0) {
+		errno = EDOM; /* ARGUMENT(x) is negative */
+		return TGHUGE;
+	}
+
+	if (x == 0) {
+		errno = ERANGE; /* ARGUMENT(x) is LITERAL(0) */
+		/* RETURN_FAILURE(CONSTANT(HUGE_VAL), A range error occurred); */
+		return TGHUGE;
+	}
+
+	/* RETURN_SUCCESS(the natural logarithm of ARGUMENT(x)); */
+	return x;
+}
+
+/***
+compute the natural logarithm of ARGUMENT(x).
+***/
+
+/*
+IMPLEMENTATION(The value returned on a domain error, CONSTANT(HUGE_VAL))
+LINK(m)
+*/
+/*
+STDC(1)
+*/