Date: Thu, 25 Jun 2009 03:41:49 -0700 (PDT)

From: adish

Subject: Re: [Boost-users] [Accumulators] Questions about the library

To: boost-users@lists.boost.org

? ?2. If my platform does not support HW floating point ops, and all my

? ?sample values are, e.g. ints, is there a way to specify that the

*computation

? ?*and *return value itself* (i.e. result_type, e.g. the mean) will be done

? ?in ints (naturally, at the cost of precision)?

I have used UDT as I needed some extra information from the results (as I was

working on data from a time series). The reverse, using a POD like int must be

possible. Instead of the first argument being float/double, use an int. If that

does not work, you can wrap an int in a UDT, implement some of the operators

like '=', '<', '/' depending on the accumulator you plan to use (I did that as I

needed to send a UDT).

Using an int still returns a float -- which is quite sensible.

You might be able to write a custom extractor which can return an int. I have not explored it. I always thought the type you give as input is the type that gets returned

It does not since the mean of integers is a floating point type. Doing means as integers will also not make much sense since the mean is calculated by dividing the sum of values by the number of values, and the sum will very soon overflow your integer. However, if you are sure that the sum will never overflow then you can define your own UDT wrapping an integer and do all the math using that type. I would not recommend doing this, though.

Matthias