clean
=====

cleans matrices (round to zero small entries)



Calling Sequence
~~~~~~~~~~~~~~~~


::

    B=clean(A [,epsa [,epsr]])




Arguments
~~~~~~~~~

:A a numerical matrix (scalar, polynomial, sparse...)
: :epsa,epsr real numbers. Cleaning tolerances (default values resp.
  1.d-10 and 1.d-10)
:



Description
~~~~~~~~~~~

This function eliminates (i.e. set to zero) all the coefficients with
absolute value < `epsa` or relative value < `epsr` (relative means
relative w.r.t. 1-norm of coefficients) in a polynomial (possibly
matrix polynomial or rational matrix).

Default values are `epsa=1.d-10` and `epsr=1.d-10;`

For a constant (non polynomial) matrix `clean(A,epsa)` sets to zero
all entries of `A` smaller than `epsa`.



Examples
~~~~~~~~


::

    x=`poly`_(0,'x');
    w=[x,1,2+x;3+x,2-x,x^2;1,2,3+x]/3;
    w*`inv`_(w)
    clean(w*`inv`_(w))