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## Diff of /inst/scale_data.m [000000] .. [afe5a1] Maximize Restore

### Switch to side-by-side view

```--- a
+++ b/inst/scale_data.m
@@ -0,0 +1,47 @@
+# Copyright (C) 2003,2004  Michael Creel <michael.creel@uab.es>
+#
+# This program is free software; you can redistribute it and/or modify
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+# Standardizes and normalizes data matrix,
+# primarily for use by BFGS
+
+function [zz, scalecoefs] = scale_data(z);
+
+	n = rows(z);
+	k = columns(z);
+
+	# Scale data
+	s = std(z)';
+	test = s != 0;
+	s = s + (1 - test); # don't scale if column is a constant (avoid div by zero)
+	A = diag(1 ./ s);
+
+	# De-mean all variables except constant, if a constant is present
+	test = std(z(:,1)) != 0;
+	if test
+		warning("ScaleData: no constant present - only scale - no de-mean");
+		bb = zeros(n,k);
+		b = zeros(k,1);
+	else
+		b = -mean(z)';
+		test = std(z)' != 0;
+		# don't take out mean if the column is a constant, to preserve identification
+		b = b .* test;
+		b = A*b;
+		bb = dmult(b, ones(k,n))';
+	endif
+	zz = z*A + bb;
+	scalecoefs = {A,b};
+endfunction
```