From 42332bb04fbde5661a4ee3ff2884c5f4e53c95f9 Mon Sep 17 00:00:00 2001
From: Alex Shinn <alexshinn@gmail.com>
Date: Sat, 14 May 2022 16:30:27 +0900
Subject: [PATCH] compute least double properly (issue #831)

---
 lib/srfi/144/math.stub | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/srfi/144/math.stub b/lib/srfi/144/math.stub
index a7f16703..27f154c1 100644
--- a/lib/srfi/144/math.stub
+++ b/lib/srfi/144/math.stub
@@ -1,6 +1,15 @@
 
 (c-system-include "math.h")
 
+(c-declare "
+double sexp_compute_least_double(double f) {
+  for (double g = f/2; g < f && g > 0; g /= 2) {
+    f = g;
+  }
+  return f;
+}
+")
+
 (define-c-const double
   (fl-e "M_E")
   (fl-1/e "1.0/M_E")
@@ -43,7 +52,7 @@
   (fl-gamma-1/3 "tgamma(1.0/3.0)")
   (fl-gamma-2/3 "tgamma(2.0/3.0)")
   (fl-greatest "DBL_MAX")
-  (fl-least "-DBL_MAX")
+  (fl-least "sexp_compute_least_double(DBL_MIN)")
   (fl-integer-exponent-zero "FP_ILOGB0")
   (fl-integer-exponent-nan "FP_ILOGBNAN")
   (fl-epsilon "DBL_EPSILON"))