From bug-octave-request at bevo dot che dot wisc dot edu Tue Nov 18 13:06:45 2003
Subject: "format +" documentation
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: taltman at lbl dot gov
Cc: bug-octave at bevo dot che dot wisc dot edu
Date: Tue, 18 Nov 2003 13:06:39 -0600

On 26-Oct-2003, taltman at lbl dot gov <taltman@lbl.gov> wrote:

| I'm using Octave 2.1.40, and I've noticed that 'format +' not only
| prints '+' and ' ' characters, but also '-'. I guess it's '+' for
| positive matrix values, '-' for negative matrix values, and ' ' for
| zero values. I think the documentation should be updated to include
| the '-' convention, and perhaps Octave could use some other
| place-holder for zero entries? It took me a while to realize that my
| entire bottom row was all zeros. ;-)

How about the following patch?  It makes the default behavior
Matlab compatible and allows you to choose the characters you would
prefer for positive, negative, and zero values.

jwe


src/ChangeLog:

2003-11-18  John W. Eaton  <jwe at bevo dot che dot wisc dot edu>

	* pr-output.cc (octave_print_internal): Don't indent rows for
	plus_format.  Use pr_plus_format for Range type with plus_format.
	(plus_format_chars): New static variable.
	(set_format_style): Allow optional arg for plus format to set it.
	(pr_plus_format): Use it.

 
Index: src/pr-output.cc
===================================================================
RCS file: /usr/local/cvsroot/octave/src/pr-output.cc,v
retrieving revision 1.114
diff -u -r1.114 pr-output.cc
--- src/pr-output.cc	31 Oct 2003 05:57:44 -0000	1.114
+++ src/pr-output.cc	18 Nov 2003 19:04:00 -0000
 at @ -82,6 +82,9 @@
 // TRUE means print plus sign for nonzero, blank for zero.
 static bool plus_format = false;
 
+// First char for > 0, second for < 0, third for == 0.
+static std::string plus_format_chars = "+  ";
+
 // TRUE means always print like dollars and cents.
 static bool bank_format = false;
 
 at @ -1341,12 +1344,12 @@
 static inline void
 pr_plus_format (std::ostream& os, double d)
 {
-  if (d == 0.0)
-    os << " ";
+  if (d > 0.0)
+    os << plus_format_chars[0];
   else if (d < 0.0)
-    os << "-";
+    os << plus_format_chars[1];
   else
-    os << "+";
+    os << plus_format_chars[2];
 }
 
 void
 at @ -1383,9 +1386,6 @@
 	    {
 	      OCTAVE_QUIT;
 
-	      if (j == 0)
-		os << "  ";
-
 	      pr_plus_format (os, m(i,j));
 	    }
 
 at @ -1644,9 +1644,6 @@
 	    {
 	      OCTAVE_QUIT;
 
-	      if (j == 0)
-		os << "  ";
-
 	      pr_plus_format (os, cm(i,j));
 	    }
 
 at @ -1794,16 +1791,13 @@
 
   if (plus_format && ! pr_as_read_syntax)
     {
-      os << "  ";
       for (int i = 0; i < num_elem; i++)
 	{
 	  OCTAVE_QUIT;
 
 	  double val = base + i * increment;
-	  if (val == 0.0)
-	    os << " ";
-	  else
-	    os << "+";
+
+	  pr_plus_format (os, val);
 	}
     }
   else
 at @ -2210,6 +2204,21 @@
 	}
       else if (arg == "+" || arg == "plus")
 	{
+	  if (--argc > 0)
+	    {
+	      arg = argv[idx++];
+
+	      if (arg.length () == 3)
+		plus_format_chars = arg;
+	      else
+		{
+		  error ("format: invalid option for plus format");
+		  return;
+		}
+	    }
+	  else
+	    plus_format_chars = "+  ";
+
 	  init_format_state ();
 	  plus_format = true;
 	}
 at @ -2336,10 +2345,27 @@
 point.\n\
 \n\
  at item +\n\
+ at itemx + @var{chars}\n\
+ at itemx plus\n\
+ at itemx plus @var{chars}\n\
 Print a  at samp{+} symbol for nonzero matrix elements and a space for zero\n\
 matrix elements.  This format can be very useful for examining the\n\
 structure of a large matrix.\n\
 \n\
+The optional argument  at var{chars} specifies a list of 3 characters to use\n\
+for printing values greater than zero, less than zero and equal to zero.\n\
+For example, with the  at samp{+ \"+-.\"} format, @code{[1, 0, -1; -1, 0, 1]}\n\
+is displayed as\n\
+\n\
+ at example\n\
+ at group\n\
+ans =\n\
+\n\
++.-\n\
+-.+\n\
+ at end group\n\
+ at end example\n\
+\n\
  at item hex\n\
 Print the hexadecimal representation numbers as they are stored in\n\
 memory.  For example, on a workstation which stores 8 byte real values\n\



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