From 1355fdbfaf2262204d63bb6cfaee80c0b0b6d65f Mon Sep 17 00:00:00 2001
From: Oldes <oldes.huhuman@gmail.com>
Date: Fri, 16 Oct 2020 00:22:07 +0200
Subject: [PATCH] FIX: `log-*` functions should not return `positive number
 required` errors

fixes: https://github.com/Oldes/Rebol-issues/issues/2432
---
 src/core/n-math.c               |  6 ++++++
 src/tests/units/decimal-test.r3 | 22 ++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/src/core/n-math.c b/src/core/n-math.c
index 7ed50170e0..2a2f5304e3 100644
--- a/src/core/n-math.c
+++ b/src/core/n-math.c
@@ -352,7 +352,9 @@ enum {SINE, COSINE, TANGENT};
 ***********************************************************************/
 {
 	REBDEC dval = AS_DECIMAL(D_ARG(1));
+#ifdef USE_NO_INFINITY
 	if (dval <= 0) Trap0(RE_POSITIVE);
+#endif
 	SET_DECIMAL(D_RET, log10(dval));
 	return R_RET;
 }
@@ -365,7 +367,9 @@ enum {SINE, COSINE, TANGENT};
 ***********************************************************************/
 {
 	REBDEC dval = AS_DECIMAL(D_ARG(1));
+#ifdef USE_NO_INFINITY
 	if (dval <= 0) Trap0(RE_POSITIVE);
+#endif
 	SET_DECIMAL(D_RET, log(dval) / LOG2);
 	return R_RET;
 }
@@ -378,7 +382,9 @@ enum {SINE, COSINE, TANGENT};
 ***********************************************************************/
 {
 	REBDEC dval = AS_DECIMAL(D_ARG(1));
+#ifdef USE_NO_INFINITY
 	if (dval <= 0) Trap0(RE_POSITIVE);
+#endif
 	SET_DECIMAL(D_RET, log(dval));
 	return R_RET;
 }
diff --git a/src/tests/units/decimal-test.r3 b/src/tests/units/decimal-test.r3
index 5fe7e1eeb0..f080950454 100644
--- a/src/tests/units/decimal-test.r3
+++ b/src/tests/units/decimal-test.r3
@@ -125,6 +125,28 @@ Rebol [
 ===end-group===
 
 
+===start-group=== "log"
+	--test-- "log-* -1"
+		;@@ https://github.com/Oldes/Rebol-issues/issues/2431
+		--assert "1.#NaN" = mold try [log-2  -1]
+		--assert "1.#NaN" = mold try [log-e  -1]
+		--assert "1.#NaN" = mold try [log-10 -1]
+		
+	--test-- "log-* 0"
+		--assert "-1.#INF" = mold try [log-2  0]
+		--assert "-1.#INF" = mold try [log-e  0]
+		--assert "-1.#INF" = mold try [log-10 0]
+
+	--test-- "log-2 32"
+		--assert 5.0 = log-2 32
+	--test-- "log-10 100"
+		--assert 2.0 = log-10 100
+	--test-- "log-e 123"
+		--assert 4.812184355372417 = log-e 123
+
+===end-group===
+
+
 ===start-group=== "decimal issues"
 	--test-- "issue-1753"
 	;@@ https://github.com/Oldes/Rebol-issues/issues/1753