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Ublas :

From: Andreas Klöckner (lists_at_[hidden])
Date: 2008-08-11 20:10:14

Hi Jeremy,

On Montag 11 August 2008, Jeremy Conlin wrote:
> I have the need to take the square root of a ublas::vector, i.e. take the
> square root of every element of the vector, independently. I tried simply
> importing <cmath> but that didn't work. Is there a ublas header somewhere
> that adds this functionality?

Try the attached header together with something like this:

8< ---------------------------------------------------------------
      struct int_ceil_functor
        typedef double value_type;
        typedef const double &argument_type;
        typedef int result_type;

        static result_type apply(argument_type x)
          return int(ceil(x));

Then use
8< ---------------------------------------------------------------

This has the advantage that it works together with Ublas's ET machinery,
giving you the option of not having a temporary. (You'll have to do some
simple knitting to make it do "sqrt" instead of "int_ceil".)