--- a/scripts/strings/dec2bin.m	Wed Apr 22 15:53:51 2020 -0700
+++ b/scripts/strings/dec2bin.m	Wed Apr 22 17:04:55 2020 -0700
@@ -24,12 +24,20 @@
 ########################################################################
 
 ## -*- texinfo -*-
-## @deftypefn {} {} dec2bin (@var{d}, @var{len})
-## 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}.
+## @deftypefn  {} {} dec2bin (@var{d})
+## @deftypefnx {} {} dec2bin (@var{d}, @var{len})
+## Return a string of ones and zeros representing the conversion of the integer
+## @var{d} to a binary number.
 ##
-## For example:
+## If @var{d} is negative, return the two's complement binary value of @var{d}.
+## If @var{d} is a matrix or cell array, return a string matrix with one row
+## for each element in @var{d}, padded with leading zeros to the width of the
+## largest value.
+##
+## The optional second argument, @var{len}, specifies the minimum number of
+## digits in the result.
+##
+## Examples:
 ##
 ## @example
 ## @group
@@ -41,49 +49,40 @@
 ## @end group
 ## @end example
 ##
-## If @var{d} is a matrix or cell array, return a string matrix with one row
-## per element in @var{d}, padded with leading zeros to the width of the
-## largest value.
-##
-## 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 (nargin == 0 || nargin > 2)
+    print_usage ();
+  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;
+  if (iscell (d))
+    d = cell2mat (d);
   endif
-endif
+  ## Create column vector for algorithm (output is always col. vector anyways)
+  d = d(:);
+  
+  lt_zero_idx = (d < 0);
+  if (any (lt_zero_idx))
+    if (any (d(lt_zero_idx) < intmin ("int64")))
+      error ('dec2bin: negative inputs cannot be less than intmin ("int64")');
+    elseif (any (d(lt_zero_idx) < intmin ("int32")))
+      d(lt_zero_idx) += double (intmax ("uint64")) + 1;
+    elseif (any (d < intmin ("int16")))
+      d(lt_zero_idx) += double (intmax ("uint32")) + 1;
+    elseif (any (d < intmin ("int8")))
+      d(lt_zero_idx) += double (intmax ("uint16"))+ 1;
+    else
+      d(lt_zero_idx) += double (intmax ("uint8")) + 1;
+    endif
+  endif
 
   if (nargin == 1)
     b = dec2base (d, 2);
-  elseif (nargin == 2)
+  else
     b = dec2base (d, 2, len);
-  else
-    print_usage ();
   endif
 
 endfunction
@@ -100,16 +99,33 @@
 %!assert (dec2bin (-3), "11111101")
 %!assert (dec2bin (-3, 3), "11111101")
 %!assert (dec2bin (-3, 9), "011111101")
-%!assert (dec2bin (-129), "1111111101111111")
+%!assert (dec2bin (-2^7 -1), "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"])
+## The expected value is correct, but not what Octave generates because
+## floating point integer precision is 2^53.  Matlab gets this right.
+%!xtest
+%! assert (dec2bin (-2^31 -1),
+%!        "1111111111111111111111111111111101111111111111111111111111111111");
+%!assert (dec2bin (-2^63),
+%!        "1000000000000000000000000000000000000000000000000000000000000000")
+## These tests also don't work because of floating point precision.
+%!xtest
+%! assert (dec2bin (int64 (-2^63)),
+%!        "1000000000000000000000000000000000000000000000000000000000000000");
+%!xtest
+%! assert (dec2bin (int64 (-2^63) -1),
+%!        "1000000000000000000000000000000000000000000000000000000000000000");
+%!xtest
+%! assert (dec2bin (int64 (-2^63) +1),
+%!        "1000000000000000000000000000000000000000000000000000000000000001");
+%!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")))
+%!error <negative inputs> dec2bin (2 * double (intmin ("int64")))