# HG changeset patch
# User dbateman
# Date 1192436574 0
# Node ID 3e2a59c78b9d56814ea1ab4f90dee53788bb455d
# Parent  b60eeac5ac381477199018b1e625a4cd0e72ffe3
[project @ 2007-10-15 08:22:54 by dbateman]

diff --git a/scripts/ChangeLog b/scripts/ChangeLog
--- a/scripts/ChangeLog
+++ b/scripts/ChangeLog
@@ -1,3 +1,8 @@
+2007-10-15  Kim Hansen  i<kimhanse@gmail.com>
+
+	* testfun/assert.m: Correct documentation of absolution versus 
+	relative error tolerance and add tests.
+
 2007-10-14  David Bateman  <dbateman@free.fr>
 
 	* pkg/pkg.m (pkg:configure_make): Treat case of no files to install in
diff --git a/scripts/testfun/assert.m b/scripts/testfun/assert.m
--- a/scripts/testfun/assert.m
+++ b/scripts/testfun/assert.m
@@ -35,10 +35,12 @@
 ## lists or structures.
 ##
 ## @item assert(@var{observed}, @var{expected}, @var{tol})
-## Produce an error if relative error is less than tolerance. That is, 
-## @code{abs(@var{observed} - @var{expected}) > @var{tol} * @var{expected}}.  
-## Absolute error @code{abs(@var{observed} - @var{expected}) > abs(@var{tol})} 
-## will be used when tolerance is negative or when the expected value is zero.
+## Accept a tolerance when comparing numbers. 
+## If @var{tol} is possitive use it as an absolute tolerance, will produce an error if
+## @code{abs(@var{observed} - @var{expected}) > abs(@var{tol})}.
+## If @var{tol} is negative use it as a relative tolerance, will produce an error if
+## @code{abs(@var{observed} - @var{expected}) > abs(@var{tol} * @var{expected})}.
+## If @var{expected} is zero @var{tol} will always be used as an absolute tolerance.
 ## @end table
 ## @seealso{test}
 ## @end deftypefn
@@ -249,7 +251,7 @@
 %!error assert(3+2*eps, 3, eps);
 %!error assert(3, 3+2*eps, eps);
 
-%## must give a little space for floating point errors on relative
+## must give a little space for floating point errors on relative
 %!assert(100+100*eps, 100, -2*eps); 
 %!assert(100, 100+100*eps, -2*eps);
 %!error assert(100+300*eps, 100, -2*eps); 
@@ -257,6 +259,12 @@
 %!error assert(3, [3,3]);
 %!error assert(3,4);
 
+## test relative vs. absolute tolerances
+%!test  assert (0.1+eps, 0.1,  2*eps);  # accept absolute
+%!error assert (0.1+eps, 0.1, -2*eps);  # fail relative
+%!test  assert (100+100*eps, 100, -2*eps);  # accept relative
+%!error assert (100+100*eps, 100,  2*eps);  # fail absolute
+
 ## structures
 %!shared x,y
 %! x.a = 1; x.b=[2, 2];