From 912ad2d3455228f3430bdf095536934ef42d1752 Mon Sep 17 00:00:00 2001
From: David Alessio <david.alessio@yahoo.com>
Date: Thu, 14 Jul 2016 20:15:37 -0600
Subject: [PATCH] Fix bug in logf() algorithm that caused erroneous INFINITY
 results.

---
 libc/math/lib_erf.c  |  3 ++-
 libc/math/lib_logf.c | 14 ++++++++------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/libc/math/lib_erf.c b/libc/math/lib_erf.c
index 1923638dba..215c101720 100644
--- a/libc/math/lib_erf.c
+++ b/libc/math/lib_erf.c
@@ -67,6 +67,7 @@ double erf(double x)
 
   sign = (x >= 0 ? 1 : -1);
   t = 1.0/(1.0 + p*x);
-  return sign * (1.0 - (((((a5 * t + a4) * t) + a3) * t + a2) * t + a1) * t * expf(-x * x));
+  return sign * (1.0 - (((((a5 * t + a4) * t) + a3) * t + a2) * t + a1) * t *
+                 (double)expf(-x * x));
 }
 #endif
diff --git a/libc/math/lib_logf.c b/libc/math/lib_logf.c
index 2d097d228e..9abc5eff98 100644
--- a/libc/math/lib_logf.c
+++ b/libc/math/lib_logf.c
@@ -32,6 +32,8 @@
 #include <math.h>
 #include <float.h>
 
+#define FLT_MAX_EXP_X   88.0F
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -50,25 +52,25 @@ float logf(float x)
       ey = exp(y);
       y -= (ey - x) / ey;
 
-      if (y > 700.0F)
+      if (y > FLT_MAX_EXP_X)
         {
-          y = 700.0F;
+          y = FLT_MAX_EXP_X;
         }
 
-      if (y < -700.0F)
+      if (y < -FLT_MAX_EXP_X)
         {
-          y = -700.0F;
+          y = -FLT_MAX_EXP_X;
         }
 
       epsilon = (fabsf(y) > 1.0F) ? fabsf(y) * FLT_EPSILON : FLT_EPSILON;
     }
 
-  if (y == 700.0F)
+  if (y == FLT_MAX_EXP_X)
     {
       return INFINITY;
     }
 
-  if (y == -700.0F)
+  if (y == -FLT_MAX_EXP_X)
     {
       return INFINITY;
     }