# HG changeset patch
# User Nicholas R. Jankowski <jankowskin@asme.org>
# Date 1587596031 25200
# Node ID 5bb1c0cbb27ed51ac8554357dbc82b027a53f9f8
# Parent  a6edb8097ec6967d3b563bf2692992357fbf87b4
dec2bin.m: Allow negative number inputs (bug #58147).

* dec2bin.m: Document that negative numbers are converted according to 2's
complement convention.  Add example to documentation of converting a
negative number.  Add algorithm to detect negative inputs and add the
appropriate offset for 2's complement notation.  Add BIST tests.

diff -r a6edb8097ec6 -r 5bb1c0cbb27e scripts/strings/dec2bin.m
--- a/scripts/strings/dec2bin.m	Wed Apr 22 13:23:05 2020 +0200
+++ b/scripts/strings/dec2bin.m	Wed Apr 22 15:53:51 2020 -0700
@@ -25,8 +25,9 @@
 
 ## -*- texinfo -*-
 ## @deftypefn {} {} dec2bin (@var{d}, @var{len})
-## Return a binary number corresponding to the non-negative integer @var{d},
-## as a string of ones and zeros.
+## Return a binary number corresponding to the integer @var{d} as a string of
+## ones and zeros.  If @var{d} is negative, return the two's complement binary
+## value of @var{d}.
 ##
 ## For example:
 ##
@@ -34,6 +35,9 @@
 ## @group
 ## dec2bin (14)
 ##      @result{} "1110"
+##
+## dec2bin (-14)
+##      @result{} "11110010"
 ## @end group
 ## @end example
 ##
@@ -43,11 +47,37 @@
 ##
 ## The optional second argument, @var{len}, specifies the minimum number of
 ## digits in the result.
+##
 ## @seealso{bin2dec, dec2base, dec2hex}
 ## @end deftypefn
 
 function b = dec2bin (d, len)
 
+## dec2base does cell->mat conversion, this allows easier content comparison
+if (iscell (d))
+  d = cell2mat (d);
+endif
+
+d = d(:);  ## output is always a column vector, (:) simplifies value checks
+
+if (any (d < intmin ("int64")))
+    error ("dec2bin: negative inputs cannot be less than intmin('int64')");
+endif
+
+if (any (d < 0))
+  if (any (d < intmin ("int64")))
+    error ("out of range");
+  elseif (any (d < intmin ("int32")))
+    d(d < 0) += double (intmax ("uint64")) + 1 ;
+  elseif (any (d < intmin ("int16")))
+    d(d < 0) += double (intmax ("uint32")) + 1;
+  elseif (any (d < intmin ("int8")))
+    d(d < 0) += double (intmax ("uint16"))+ 1;
+  else
+    d(d < 0) += double (intmax ("uint8")) +1;
+  endif
+endif
+
   if (nargin == 1)
     b = dec2base (d, 2);
   elseif (nargin == 2)
@@ -59,10 +89,27 @@
 endfunction
 
 
+%!assert (dec2bin (3), "11")
 %!assert (dec2bin (14), "1110")
 %!assert (dec2bin (14, 6), "001110")
+%!assert (dec2bin ([1, 2; 3, 4]), ["001"; "011"; "010"; "100"])
 %!assert (dec2bin ({1, 2; 3, 4}), ["001"; "011"; "010"; "100"])
+%!assert (dec2bin ({1, 2; 3, 4}, 4), ["0001"; "0011"; "0010"; "0100"])
+
+## Test negative inputs
+%!assert (dec2bin (-3), "11111101")
+%!assert (dec2bin (-3, 3), "11111101")
+%!assert (dec2bin (-3, 9), "011111101")
+%!assert (dec2bin (-129), "1111111101111111")
+%!assert (dec2bin (-2^15 -1), "11111111111111110111111111111111")
+%!assert (dec2bin (-2^31 -1), "1111111111111111111111111111111101111111111111111111111111111111")
+%!assert (dec2bin (-2^63), "1000000000000000000000000000000000000000000000000000000000000000")
+%!assert (dec2bin (-2^63-1), "1000000000000000000000000000000000000000000000000000000000000000")
+%!assert (dec2bin ([-1, -2; -3, -4]), ["11111111"; "11111101"; "11111110"; "11111100"])
+%!assert (dec2bin ([1, 2; 3, -4]), ["00000001"; "00000011"; "00000010"; "11111100"])
+%!assert (dec2bin ({1, 2; 3, -4}), ["00000001"; "00000011"; "00000010"; "11111100"])
 
 ## Test input validation
 %!error dec2bin ()
 %!error dec2bin (1, 2, 3)
+%!error dec2bin (2 * double (intmin ("int64")))