submat_noeval

Returns the input matrix reduced along indicated dimensions (without eval)

Description

This is similar to the submat function I submitted earlier (file id 19324) except that it does not use EVAL. Accordingly it loses the flexibility offered by EVAL.

This is a function to aid/simplify access to subsections of a n-d matrix.

Y=SUBMAT_NOEVAL(X,DIM,LIST) creates a matrix Y that is the matrix X reduced along dimension DIM to the indices in LIST. If DIM is a list of dimensions, LIST is used to reduce each dimension.

Y=SUBMAT_NOEVAL(X,DIM1,LIST1,DIM2,LIST2,...) allows for access to multiple dimensions independently.

Acknowledgements

The author wishes to acknowledge the following in the creation of this submission:
submat
This submission has inspired the following:
subarray

• MATLAB release: MATLAB 7.5 (R2007b)

[Duane Hanselman]

Since you did not simply update your previous submission of the same name, please delete it today. It is inappropriate to have two identically named functions from the same author.

[Jos x@y.z]

I have some problems understanding this code:
Apparently, -- Y = submat_noeval(X,D,F) -- is the same as -- ind(1:ndims(X)) = {':'} ; ind{D} = F ; Y = X(ind{:}) --

which would allow for a much simpler code:
Y = fun(X,varargin)
ind(1:ndims(X)) = {':'} ;
i = 1:2:nargin-1 ;
ind{[varargin{i}]} = deal(varargin{i+1}) ;
Y = X(ind{:}) ;

Please correct me if I am wrong ...

[Garrett Euler]

Yea I did not know that one. Matlab takes the string ':' as a special case when indexing matrices...anything else like '1:2' etc though doesn't work without an eval. Thanks, I'll update!