The module "screed" of the Mastrave modelling library

Copyright and license notice of the function screed

Copyright © 2007,2008,2009 Daniele de Rigo The file screed.m is part of Mastrave. Mastrave is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. Mastrave is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Mastrave. If not, see http://www.gnu.org/licenses/.

Function declaration

Copyright (C) 

Description

2007,2008,2009 Daniele de Rigo This file is part of Mastrave. Mastrave is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. Mastrave is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Mastrave. If not, see <http://www.gnu.org/licenses/>. --------------------------------------------------------------------------- [ screeded_vals , valley_set ] = screed( vals, threshold, method ) Given a matrix vals and a threshold , the values of vals around the minimum are located as the valley_set according to one of the allowed method s that use threshold to.

Input arguments

 vals            ::numeric::
                 scalar, vector or matrix of numeric values

 threshold       ::nonnegative::
                 non negative scalar or 2-dimensional vector

 method          ::cellstring::
                 method to be used to locate the  valley_set  and to connect
                 the valley set with the subset Uvals of untouched  vals .
                 Follows here a list of the implemented  method s
                 (it can be passed in  method  only one method for each set):

          normalization methods │ meaning
       ─────────────────────────┼───────────────────────────────────────────
                  'lin'         │ linear mapping where
                                │    min(vals(:)) -> 0
                                │    max(vals(:)) -> 1
       ─────────────────────────┼───────────────────────────────────────────
                  'lin-m'       │ linear mapping where
                                │    min(vals(:)) -> 0
                                │    max(vals)    -> 1 (one for each column)
       ─────────────────────────┼───────────────────────────────────────────
                  'log'         │ logarithmic mapping where
                                │    min(vals(:)) -> 0
                                │    max(vals(:)) -> 1
       ─────────────────────────┼───────────────────────────────────────────
                  'log-m'       │ logarithmic mapping where
                                │    min(vals(:)) -> 0
                                │    max(vals)    -> 1 (one for each column)
       ─────────────────────────┼───────────────────────────────────────────

          connection methods    │ meaning
       ─────────────────────────┼───────────────────────────────────────────
                  'slide'       │ connects  valley_set  with Uvals using a
                                │ curve having the 1st derivative -> inf
                                │ near  valley_set  and the same as that of
                                │ Uvals when the curve is near Uvals
       ─────────────────────────┼───────────────────────────────────────────
                  'spline1'     │ connects  valley_set  with Uvals using a
                                │ curve that linearly stretches the subset
                                │ of  vals  between  valley_set  and Uvals
       ─────────────────────────┼───────────────────────────────────────────
                  'spline3'     │ connects  valley_set  with Uvals using a
                                │ C1 differentiability class curve, i.e. a
                                │ cubic stretching of the subset of  vals 
                                │ between  valley_set  and Uvals
       ─────────────────────────┼───────────────────────────────────────────
                  'spline5'     │ connects  valley_set  with Uvals using a
                                │ C2 differentiability class curve, i.e. a
                                │ quintic stretching of the subset of  vals 
                                │ between  valley_set  and Uvals
       ─────────────────────────┼───────────────────────────────────────────
                  'spline7'     │ connects  valley_set  with Uvals using a
                                │ C3 differentiability class curve, i.e. a
                                │ septic stretching of the subset of  vals 
                                │ between  valley_set  and Uvals
       ─────────────────────────┼───────────────────────────────────────────
                  'spline9'     │ connects  valley_set  with Uvals using a
                                │ C4 differentiability class curve, i.e. a
                                │ nonic stretching of the subset of  vals 
                                │ between  valley_set  and Uvals
       ─────────────────────────┼───────────────────────────────────────────

Example of usage

   dx = 0.01;
   x  = 0:dx:3*pi; y = sin(x);
   y1 = screed( y , [.2 .4] );
   figure(1); plot(  x , [y;y1]' )
   title( 'function and screed function' )
   xd = mean( [ x(1:end-1) ; x(2:end) ] );
   figure(2); plot( xd , diff([y;y1]')./dx )
   title( 'derivative of function and screed function' )

   method = { 'lin' , 'slide' }
   y1 = screed( y , [.2 .4] , method );
   figure(3); plot(  x , [y;y1]' )
   title( 'function and screed function' )
   xd = mean( [ x(1:end-1) ; x(2:end) ] );
   figure(4); plot( xd , diff([y;y1]')./dx )
   title( 'derivative of function and screed function' )

   method = { 'log' , 'spline5' }
   y1 = screed( y , [.2 .4] , method );
   figure(5); plot(  x , [y;y1]' )
   title( 'function and screed function' )
   xd = mean( [ x(1:end-1) ; x(2:end) ] );
   figure(6); plot( xd , diff([y;y1]')./dx )
   title( 'derivative of function and screed function' )

   method = { 'log' , 'spline9' }
   y1 = screed( y , [.2 .4] , method );
   figure(6); plot(  x , [y;y1]' )
   title( 'function and screed function' )
   xd = mean( [ x(1:end-1) ; x(2:end) ] );
   figure(7); plot( xd , diff([y;y1]')./dx )
   title( 'derivative of function and screed function' )

version: 0.3.7

Support

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