4 files changed, 59 insertions, 0 deletions
diff --git a/sal/inc/rtl/math.h b/sal/inc/rtl/math.h
index 01df54fc6..d954e7810 100644
--- a/sal/inc/rtl/math.h
+++ b/sal/inc/rtl/math.h
@@ -406,6 +406,24 @@ double SAL_CALL rtl_math_pow10Exp(double fValue, int nExp) SAL_THROW_EXTERN_C();
   */
 double SAL_CALL rtl_math_approxValue(double fValue) SAL_THROW_EXTERN_C();
 
+/** Returns more accurate e^x-1 for x near 0 than calculating directly.
+
+    expm1 is part of the C99 standard, but not provided by some compilers.
+
+    @param fValue
+    The value x in the term e^x-1.
+  */
+double SAL_CALL rtl_math_expm1(double fValue) SAL_THROW_EXTERN_C();
+
+/** Returns more accurate log(1+x) for x near 0 than calculating directly.
+
+    log1p is part of the C99 standard, but not provided by some compilers.
+
+    @param fValue
+    The value x in the term log(1+x).
+  */
+double SAL_CALL rtl_math_log1p(double fValue) SAL_THROW_EXTERN_C();
+
 #if defined __cplusplus
 }
 #endif /* __cplusplus */
diff --git a/sal/inc/rtl/math.hxx b/sal/inc/rtl/math.hxx
index c93e7de4e..724d2d102 100644
--- a/sal/inc/rtl/math.hxx
+++ b/sal/inc/rtl/math.hxx
@@ -200,6 +200,20 @@ inline double approxValue(double fValue)
     return rtl_math_approxValue(fValue);
 }
 
+/** A wrapper around rtl_math_expm1.
+ */
+inline double expm1(double fValue)
+{
+    return rtl_math_expm1(fValue);
+}
+
+/** A wrapper around rtl_math_log1p.
+ */
+inline double log1p(double fValue)
+{
+    return rtl_math_log1p(fValue);
+}
+
 /** Test equality of two values with an accuracy of the magnitude of the
     given values scaled by 2^-48 (4 bits roundoff stripped).
 
diff --git a/sal/rtl/source/math.cxx b/sal/rtl/source/math.cxx
index fde2a16cb..6258f3faf 100644
--- a/sal/rtl/source/math.cxx
+++ b/sal/rtl/source/math.cxx
@@ -959,3 +959,24 @@ double SAL_CALL rtl_math_approxValue( double fValue ) SAL_THROW_EXTERN_C()
 
     return bSign ? -fValue : fValue;
 }
+
+
+double SAL_CALL rtl_math_expm1( double fValue ) SAL_THROW_EXTERN_C()
+{
+    double fe = exp( fValue );
+    if (fe == 1.0)
+        return fValue;
+    if (fe-1.0 == -1.0)
+        return -1.0;
+    return (fe-1.0) * fValue / log(fe);
+}
+
+
+double SAL_CALL rtl_math_log1p( double fValue ) SAL_THROW_EXTERN_C()
+{
+    double fp = 1.0 + fValue;
+    if (fp == 1.0)
+        return fValue;
+    else
+        return log(fp) * fValue / (fp-1.0);
+}
diff --git a/sal/util/sal.map b/sal/util/sal.map
index 7173eac26..6104625d1 100755
--- a/sal/util/sal.map
+++ b/sal/util/sal.map
@@ -575,6 +575,12 @@ UDK_3.8 { # OOo 3.0
         rtl_math_approxValue;
 } UDK_3.7;
 
+UDK_3.9 { # OOo 3.1
+    global:
+        rtl_math_expm1;
+        rtl_math_log1p;
+} UDK_3.8;
+
 PRIVATE_1.0 {
     global:
         osl_detail_ObjectRegistry_storeAddresses;