add range utils

lib/utils/range.m

@@ -0,0 +1,21 @@
+function y = range(x,dim)
+%RANGE  Sample range.
+%   Y = RANGE(X) returns the range of the values in X.  For a vector input,
+%   Y is the difference between the maximum and minimum values.  For a
+%   matrix input, Y is a vector containing the range for each column.  For
+%   N-D arrays, RANGE operates along the first non-singleton dimension.
+%
+%   RANGE treats NaNs as missing values, and ignores them.
+%
+%   Y = RANGE(X,DIM) operates along the dimension DIM.
+%
+%   See also BOUNDS, MIN, MAX, IQR, MAD, STD.
+
+%   Copyright 1993-2016 The MathWorks, Inc.
+
+
+if nargin < 2
+    y = max(x) - min(x);
+else
+    y = max(x,[],dim) - min(x,[],dim);
+end