Home > sgwt_toolbox > sgwt_setscales.m

sgwt_setscales

PURPOSE ^

sgwt_setscales : Compute a set of wavelet scales adapted to spectrum bounds

SYNOPSIS ^

function s=sgwt_setscales(lmin,lmax,Nscales)

DESCRIPTION ^

 sgwt_setscales : Compute a set of wavelet scales adapted to spectrum bounds

 function s=sgwt_setscales(lmin,lmax,Nscales)
 
 returns a (possibly good) set of wavelet scales given minimum nonzero and 
 maximum eigenvalues of laplacian
 
 returns scales logarithmicaly spaced between minimum and maximum
 "effective" scales : i.e. scales below minumum or above maximum
 will yield the same shape wavelet (due to homogoneity of sgwt kernel : 
 currently assuming sgwt kernel g given as abspline with t1=1, t2=2)

 Inputs : 
 lmin,lmax - minimum nonzero and maximum eigenvalue of
             Laplacian. Note that in design of transform with
             scaling function, lmin may be taken just as a fixed
             fraction of lmax,  and may not actually be the
             smallest nonzero eigenvalue 
 Nscales - # of wavelet scales

 Outputs :
 s - wavelet scales

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 % sgwt_setscales : Compute a set of wavelet scales adapted to spectrum bounds
0002 %
0003 % function s=sgwt_setscales(lmin,lmax,Nscales)
0004 %
0005 % returns a (possibly good) set of wavelet scales given minimum nonzero and
0006 % maximum eigenvalues of laplacian
0007 %
0008 % returns scales logarithmicaly spaced between minimum and maximum
0009 % "effective" scales : i.e. scales below minumum or above maximum
0010 % will yield the same shape wavelet (due to homogoneity of sgwt kernel :
0011 % currently assuming sgwt kernel g given as abspline with t1=1, t2=2)
0012 %
0013 % Inputs :
0014 % lmin,lmax - minimum nonzero and maximum eigenvalue of
0015 %             Laplacian. Note that in design of transform with
0016 %             scaling function, lmin may be taken just as a fixed
0017 %             fraction of lmax,  and may not actually be the
0018 %             smallest nonzero eigenvalue
0019 % Nscales - # of wavelet scales
0020 %
0021 % Outputs :
0022 % s - wavelet scales
0023 
0024 % This file is part of the SGWT toolbox (Spectral Graph Wavelet Transform toolbox)
0025 % Copyright (C) 2010, David K. Hammond.
0026 %
0027 % The SGWT toolbox is free software: you can redistribute it and/or modify
0028 % it under the terms of the GNU General Public License as published by
0029 % the Free Software Foundation, either version 3 of the License, or
0030 % (at your option) any later version.
0031 %
0032 % The SGWT toolbox is distributed in the hope that it will be useful,
0033 % but WITHOUT ANY WARRANTY; without even the implied warranty of
0034 % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
0035 % GNU General Public License for more details.
0036 %
0037 % You should have received a copy of the GNU General Public License
0038 % along with the SGWT toolbox.  If not, see <http://www.gnu.org/licenses/>.
0039 
0040 
0041 function s=sgwt_setscales(lmin,lmax,Nscales)
0042   t1=1;
0043   t2=2;
0044   
0045   smin=t1/lmax;
0046   smax=t2/lmin;
0047   s=exp(linspace(log(smin),log(smax),Nscales));
0048

Generated on Tue 04-May-2010 16:00:20 by m2html © 2003