Merged in lokeshbv/l-nuttx/libc_math (pull request #439)

Libc math: Error fixes in modf() and ceil() API's

Approved-by: Gregory Nutt <gnutt@nuttx.org>

libc/math/lib_ceil.c

@@ -41,8 +41,10 @@
 #ifdef CONFIG_HAVE_DOUBLE
 double ceil(double x)
 {
+  double x1 = x;
+
   modf(x, &x);
-  if (x > 0.0)
+  if (x1 > 0.0 && fabs(x1 - x) > 0.0)
     {
       x += 1.0;
     }

libc/math/lib_ceilf.c

@@ -37,8 +37,10 @@
 
 float ceilf(float x)
 {
+  float x1 = x;
+
   modff(x, &x);
-  if (x > 0.0F)
+  if (x1 > 0.0F && fabsf(x1 - x) > 0.0F)
     {
       x += 1.0F;
     }

libc/math/lib_ceill.c

@@ -41,8 +41,10 @@
 #ifdef CONFIG_HAVE_LONG_DOUBLE
 long double ceill(long double x)
 {
+  long double x1 = x;
+
   modfl(x, &x);
-  if (x > 0.0)
+  if (x1 > 0.0 && fabsl(x1 - x) > 0.0)
     {
       x += 1.0;
     }

libc/math/lib_modf.c

@@ -46,7 +46,7 @@ double modf(double x, double *iptr)
     }
   else if (fabs(x) < 1.0)
     {
-      *iptr = 0.0;
+      *iptr = (x * 0.0);
       return x;
     }
   else

libc/math/lib_modff.c

@@ -44,7 +44,7 @@ float modff(float x, float *iptr)
     }
   else if (fabsf(x) < 1.0F)
     {
-      *iptr = 0.0F;
+      *iptr = (x * 0.0F);
       return x;
     }
   else

libc/math/lib_modfl.c

@@ -49,7 +49,7 @@ long double modfl(long double x, long double *iptr)
     }
   else if (fabs(x) < 1.0)
     {
-      *iptr = 0.0;
+      *iptr = (x * 0.0);
       return x;
     }
   else