ivan@78: function  x = SoftTh(y,thld)
ivan@78: %    x = SoftTh(y,thld); 
ivan@78: %
ivan@78: %    SOFTTH soft thresholds the input signal y with the threshold value
ivan@78: %    thld.
ivan@78: %
ivan@78: %    Input:  
ivan@78: %       y    : 1D or 2D signal to be thresholded
ivan@78: %       thld : Threshold value
ivan@78: %
ivan@78: %    Output: 
ivan@78: %       x : Soft thresholded output (x = sign(y)(|y|-thld)_+)
ivan@78: %
ivan@78: %  HERE'S AN EASY WAY TO RUN THE EXAMPLES:
ivan@78: %  Cut-and-paste the example you want to run to a new file 
ivan@78: %  called ex.m, for example. Delete out the % at the beginning 
ivan@78: %  of each line in ex.m (Can use search-and-replace in your editor
ivan@78: %  to replace it with a space). Type 'ex' in matlab and hit return.
ivan@78: %
ivan@78: %
ivan@78: %    Example:
ivan@78: %       y = makesig('Doppler',8);
ivan@78: %       thld = 0.2;
ivan@78: %       x = SoftTh(y,thld)
ivan@78: %       x = 0 0 0 -0.0703 0 0.2001 0.0483 0 
ivan@78: %
ivan@78: %    See also: HardTh
ivan@78: %
ivan@78: %    Reference: 
ivan@78: %       "De-noising via Soft-Thresholding" Tech. Rept. Statistics,
ivan@78: %       Stanford, 1992. D.L. Donoho.
ivan@78: %
ivan@78: 
ivan@78: %File Name: SoftTh.m
ivan@78: %Last Modification Date: 8/15/95	17:49:48
ivan@78: %Current Version: SoftTh.m	2.4
ivan@78: %File Creation Date: Mon Mar  7 10:38:45 1994
ivan@78: %Author: Haitao Guo  <harry@jazz.rice.edu>
ivan@78: %
ivan@78: %Copyright (c) 2000 RICE UNIVERSITY. All rights reserved.
ivan@78: %Created by Haitao Guo, Department of ECE, Rice University. 
ivan@78: %
ivan@78: %This software is distributed and licensed to you on a non-exclusive 
ivan@78: %basis, free-of-charge. Redistribution and use in source and binary forms, 
ivan@78: %with or without modification, are permitted provided that the following 
ivan@78: %conditions are met:
ivan@78: %
ivan@78: %1. Redistribution of source code must retain the above copyright notice, 
ivan@78: %   this list of conditions and the following disclaimer.
ivan@78: %2. Redistribution in binary form must reproduce the above copyright notice, 
ivan@78: %   this list of conditions and the following disclaimer in the 
ivan@78: %   documentation and/or other materials provided with the distribution.
ivan@78: %3. All advertising materials mentioning features or use of this software 
ivan@78: %   must display the following acknowledgment: This product includes 
ivan@78: %   software developed by Rice University, Houston, Texas and its contributors.
ivan@78: %4. Neither the name of the University nor the names of its contributors 
ivan@78: %   may be used to endorse or promote products derived from this software 
ivan@78: %   without specific prior written permission.
ivan@78: %
ivan@78: %THIS SOFTWARE IS PROVIDED BY WILLIAM MARSH RICE UNIVERSITY, HOUSTON, TEXAS, 
ivan@78: %AND CONTRIBUTORS AS IS AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, 
ivan@78: %BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
ivan@78: %FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RICE UNIVERSITY 
ivan@78: %OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
ivan@78: %EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
ivan@78: %PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 
ivan@78: %OR BUSINESS INTERRUPTIONS) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
ivan@78: %WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
ivan@78: %OTHERWISE), PRODUCT LIABILITY, OR OTHERWISE ARISING IN ANY WAY OUT OF THE 
ivan@78: %USE OF THIS SOFTWARE,  EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
ivan@78: %
ivan@78: %For information on commercial licenses, contact Rice University's Office of 
ivan@78: %Technology Transfer at techtran@rice.edu or (713) 348-6173
ivan@78: %
ivan@78: %Change History:
ivan@78: %
ivan@78: 
ivan@78: x = abs(y);
ivan@78: x = sign(y).*(x >= thld).*(x - thld);