The module "cumsumsq" of the Mastrave modelling library

Copyright and license notice of the function cumsumsq

Copyright © 2006,2007,2008,2009,2010,2011 Daniele de Rigo

The file cumsumsq.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

answer = cumsumsq( values      ,
                   dim    = [] )

Description

Utility to extend the function sumsq(.) providing cumulative sum of squared elements of the array values along a given dimension dim .

Input arguments

 values            ::numeric::
                   Vector, matrix or multi-dimensional array of numbers.

 dim               ::scalar_index|empty::
                   Scalar positive integer representing the dimension along
                   which the cumulative sum of squared elements have to be
                   computed.
                   If  dim  is an empty array  [] , the dimension is the 
                   first non-singleton dimension.  In case  values  is a
                   vector, this definition means that the default
                   dimension is the one along which the elements of the
                   vector  values  are aligned.
                   If omitted, the default value is  [] .

Example of usage

   % Basic usage

   % Vectors:
   v    = ceil( rand(1,7)* 100 )
   cs   = cumsumsq( v )
   assert( cs(end) == sumsq(v) );

   % Matrices:
   v    = ceil( rand(5,7)* 100 )
   cs   = cumsumsq( v )
   assert( cs(end,:) == sumsq(v) );
   

   % Passing a custom dimension
   cs   = cumsumsq( v , 2 )
   assert( cs(:,end) == sumsq(v,2) );

   % Dealing with multi-dimensional arrays
   v    = ceil( rand(5,7,3)* 100 )
   cs   = cumsumsq( v )
   cs   = cumsumsq( v , [] )
   assert( cs(end,:,:) == sumsq(v) );

   cs   = cumsumsq( v , 3 )
   assert( cs(:,:,end) == sumsq(v,3) );


   % Complex-valued elements of  values 
   v    = ceil( rand(5,7)* 100 ) +1i * ceil( rand(5,7)* 100 )
   cs   = cumsumsq( v )
   assert( cs(end,:) == sumsq(v) );
   cs   = cumsumsq( v , 2 )
   assert( cs(:,end) == sumsq(v,2) );    

Memory requirements:
   O( numel(  values  ) )



See also:
   cummean, cumvar, cumstd, groupfun



Keywords:
   cumulative operators, scan



Version: 0.3.2

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