# fevalArrays

## PURPOSE

Used to apply the same operation to a stack of array elements.

## SYNOPSIS

function B = fevalArrays( A, fHandle, varargin )

## DESCRIPTION

     Used to apply the same operation to a stack of array elements.

     The only constraint on the function specified in fHandle is that given
     two differrent input arrays a1 and a2, if a1 and a2 have the same
     dimensions then the outputs b1 and b2 must have the same dimensions. For
     long operations shows progress information.

     A can have arbitrary dimension.  Suppose A has size d1 x d2 ... x dn.
     Then for the purpose of this function A has dn elements, where
     A(:,:,...,i) is the ith element.  This function then applies the
     operation in fHandle, with paramters given in varargin, to each element
     in A. The results are returned in the array B, of size f1 x f2 x ... x fk
     x dn.  Each of the n element of B of the form B(:,:,...,i) is the the
     result of applying fHandle to A(:,:,...,i).  A may also be a cell array,
     see the last example.

     A limitation of fevalArrays is that it does not pass state information
     to fHandle.  For example, fHandle may want to know how many times it's
     been called.  This can be overcome by saving state information inside
     fHandle using 'persistent' variables.  For an example see imwrite2.

     USAGE
      B = fevalArrays( A, fHandle, varargin )

     INPUTS
      A        - input array
      fHandle  - operation to apply to each 'element' of A
      params   - [varargin] parameters for each operation specified by fHandle

     OUTPUTS
      B        - output array

     EXAMPLE
      B = fevalArrays( A, @rgb2gray );      % where A is MxNx3xR
      B = fevalArrays( A, @imresize, .5 );  % where A is MxNxR
      B = fevalArrays( A, @imNormalize );   % where A has arbitrary dims
      B = fevalArrays( A, @(x) {imresize(x{1},.5)} ); % A is cell array

     See also FEVALIMAGES, FEVALMATS, ARRAYFUN
     IMWRITE2, PERSISTENT, TICSTATUS,

     Piotr's Image&Video Toolbox      Version 2.0
     Copyright 2008 Piotr Dollar.  [pdollar-at-caltech.edu]
     Please email me if you find bugs, or have suggestions or questions!
     Licensed under the Lesser GPL [see external/lgpl.txt]

## CROSS-REFERENCE INFORMATION

This function calls:

- ticStatus Used to display the progress of a long process.
- tocStatus Used to display the progress of a long process.

This function is called by:

- pcaRandVec Generate random vectors in PCA subspace.
- imwrite2 Similar to imwrite, except follows a strict naming convention.
- movieToImages Creates a stack of images from a matlab movie M.