# HG changeset patch
# User John W. Eaton <jwe@octave.org>
# Date 1349358487 14400
# Node ID ecf5be238b4aa9348d4c87c710b9615c0daed29e
# Parent  afc002de3ade9673ce32b9d6918f7b0a261965ea
provide signbit mapper for real values

* mappers.cc (Fsignbit): New function and tests.
* ov-base.cc (octave_base_value::get_umap_name): Include signbit in
the list.
* ov-base.h (octave_base_value::unary_mapper_t): Include umap_xsignbit
in the list.
* ov-float.cc (octave_float_scalar::map): Handle xsignbit.
* ov-scalar.cc (octave_scalar::map): Handle xsignbit.
* ov-re-mat.cc (octave_matrix::map): Handle xsignbit.
* ov-flt-re-mat.cc (octave_float_matrix::map): Handle xsignbit.
* lo-mappers.h (xsignbit): New template function.
* arith.txi: Document signbit.

diff --git a/doc/interpreter/arith.txi b/doc/interpreter/arith.txi
--- a/doc/interpreter/arith.txi
+++ b/doc/interpreter/arith.txi
@@ -262,6 +262,8 @@
 
 @DOCSTRING(sign)
 
+@DOCSTRING(signbit)
+
 @node Special Functions
 @section Special Functions
 
diff --git a/libinterp/corefcn/mappers.cc b/libinterp/corefcn/mappers.cc
--- a/libinterp/corefcn/mappers.cc
+++ b/libinterp/corefcn/mappers.cc
@@ -1780,6 +1780,40 @@
 %!error sign (1, 2)
 */
 
+DEFUNX ("signbit", Fsignbit, args, ,
+    "-*- texinfo -*-\n\
+@deftypefn {Mapping Function} {} signbit (@var{x})\n\
+Return a nonzero value if the value of @var{x} has its sign bit set.\n\
+\n\
+This is not the same as @code{x < 0.0}, because IEEE 754 floating point\n\
+allows zero to be signed.  The comparison @code{-0.0 < 0.0} is false,\n\
+but @code{signbit (-0.0)} will return a nonzero value.\n\
+@end deftypefn")
+{
+  octave_value retval;
+  if (args.length () == 1)
+    retval = args(0).xsignbit ();
+  else
+    print_usage ();
+
+  return retval;
+}
+
+/*
+%!assert (signbit (1) == 0)
+%!assert (signbit (-2) != 0)
+%!assert (signbit (0) == 0)
+%!assert (signbit (-0) != 0)
+
+%!assert (signbit (single (1)) == 0)
+%!assert (signbit (single (-2)) != 0)
+%!assert (signbit (single (0)) == 0)
+%!assert (signbit (single (-0)) != 0)
+
+%!error sign ()
+%!error sign (1, 2)
+*/
+
 DEFUN (sin, args, ,
     "-*- texinfo -*-\n\
 @deftypefn {Mapping Function} {} sin (@var{x})\n\
diff --git a/libinterp/octave-value/ov-base.cc b/libinterp/octave-value/ov-base.cc
--- a/libinterp/octave-value/ov-base.cc
+++ b/libinterp/octave-value/ov-base.cc
@@ -1229,6 +1229,7 @@
       "isspace",
       "isupper",
       "isxdigit",
+      "signbit",
       "toascii",
       "tolower",
       "toupper"
diff --git a/libinterp/octave-value/ov-base.h b/libinterp/octave-value/ov-base.h
--- a/libinterp/octave-value/ov-base.h
+++ b/libinterp/octave-value/ov-base.h
@@ -725,6 +725,7 @@
       umap_xisspace,
       umap_xisupper,
       umap_xisxdigit,
+      umap_xsignbit,
       umap_xtoascii,
       umap_xtolower,
       umap_xtoupper,
diff --git a/libinterp/octave-value/ov-float.cc b/libinterp/octave-value/ov-float.cc
--- a/libinterp/octave-value/ov-float.cc
+++ b/libinterp/octave-value/ov-float.cc
@@ -321,6 +321,7 @@
       SCALAR_MAPPER (isinf, xisinf);
       SCALAR_MAPPER (isna, octave_is_NA);
       SCALAR_MAPPER (isnan, xisnan);
+      SCALAR_MAPPER (xsignbit, xsignbit);
 
     default:
       return octave_base_value::map (umap);
diff --git a/libinterp/octave-value/ov-flt-re-mat.cc b/libinterp/octave-value/ov-flt-re-mat.cc
--- a/libinterp/octave-value/ov-flt-re-mat.cc
+++ b/libinterp/octave-value/ov-flt-re-mat.cc
@@ -806,6 +806,7 @@
       ARRAY_MAPPER (tan, float, ::tanf);
       ARRAY_MAPPER (tanh, float, ::tanhf);
       ARRAY_MAPPER (isna, bool, octave_is_NA);
+      ARRAY_MAPPER (xsignbit, float, xsignbit);
 
     default:
       return octave_base_value::map (umap);
diff --git a/libinterp/octave-value/ov-re-mat.cc b/libinterp/octave-value/ov-re-mat.cc
--- a/libinterp/octave-value/ov-re-mat.cc
+++ b/libinterp/octave-value/ov-re-mat.cc
@@ -929,6 +929,7 @@
       ARRAY_MAPPER (tan, double, ::tan);
       ARRAY_MAPPER (tanh, double, ::tanh);
       ARRAY_MAPPER (isna, bool, octave_is_NA);
+      ARRAY_MAPPER (xsignbit, double, xsignbit);
 
     default:
       if (umap >= umap_xisalnum && umap <= umap_xtoupper)
diff --git a/libinterp/octave-value/ov-scalar.cc b/libinterp/octave-value/ov-scalar.cc
--- a/libinterp/octave-value/ov-scalar.cc
+++ b/libinterp/octave-value/ov-scalar.cc
@@ -337,6 +337,7 @@
       SCALAR_MAPPER (isinf, xisinf);
       SCALAR_MAPPER (isna, octave_is_NA);
       SCALAR_MAPPER (isnan, xisnan);
+      SCALAR_MAPPER (xsignbit, xsignbit);
 
     default:
       if (umap >= umap_xisalnum && umap <= umap_xtoupper)
diff --git a/libinterp/octave-value/ov.h b/libinterp/octave-value/ov.h
--- a/libinterp/octave-value/ov.h
+++ b/libinterp/octave-value/ov.h
@@ -1166,6 +1166,7 @@
   MAPPER_FORWARD (xisspace)
   MAPPER_FORWARD (xisupper)
   MAPPER_FORWARD (xisxdigit)
+  MAPPER_FORWARD (xsignbit)
   MAPPER_FORWARD (xtoascii)
   MAPPER_FORWARD (xtolower)
   MAPPER_FORWARD (xtoupper)
diff --git a/liboctave/numeric/lo-mappers.h b/liboctave/numeric/lo-mappers.h
--- a/liboctave/numeric/lo-mappers.h
+++ b/liboctave/numeric/lo-mappers.h
@@ -401,4 +401,11 @@
   return retval;
 }
 
+template <typename T>
+T
+xsignbit (T x)
+{
+  return signbit (x);
+}
+
 #endif