diff --git a/.gitignore b/.gitignore
index b24af09..3911c29 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,6 @@
 *.mltbx
 *.prj
 *.prj
+*.html
+*.mltbx
+*.prj
diff --git a/gx2pdf.m b/gx2pdf.m
index bb02db6..7e6fc40 100644
--- a/gx2pdf.m
+++ b/gx2pdf.m
@@ -61,7 +61,7 @@
     addParameter(parser,'AbsTol',1e-10,@(x) isreal(x) && isscalar(x) && (x>=0));
     addParameter(parser,'RelTol',1e-6,@(x) isreal(x) && isscalar(x) && (x>=0));
     [~,v]=gx2stat(w,k,lambda,m,s);
-    addParameter(parser,'dx',sqrt(v)/100,@(x) isreal(x) && isscalar(x) && (x>=0)); % default derivative step-size is sd/100.
+    addParameter(parser,'dx',sqrt(v)/500,@(x) isreal(x) && isscalar(x) && (x>=0)); % default derivative step-size is sd/100.
     parse(parser,x,w,k,lambda,m,s,varargin{:});
     dx=parser.Results.dx;
     method=parser.Results.method;