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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] conservative resize ...
- From: Márton Danóczy <marton78@xxxxxxxxx>
- Date: Fri, 4 Sep 2009 09:42:10 +0200
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Hi,
I do think there is a use case to init memory with something else than
zero: for cumulative products with 1, for finding maxima with
-infinity, for finding minima with +infinity. And to give an example
for an arbitrary value, let's take repeated (=parallel) integrations
of a stochastic differential equation with the same initial value.
Therefore I prefer Hauke's original API.
Marton
2009/9/4 Benoit Jacob <jacob.benoit.1@xxxxxxxxx>:
> Hi,
>
> In your initial interface, allowing to extend by any arbitrary value,
> I don't think there was much of a use case for extending by a value
> other than zero. So I don't think it's a loss at all, not to have this
> feature. I like your current API,
>
> void conservativeResize(int rows, int cols, bool init_with_zero = false)
>
> How about defining a constant like
>
> const bool ExtendByZero = true;
>
> so that the user's code looks more explicit?
>
> Also, I don't know if the performance difference matters here, but if
> you want to get rid of the "if" you can always do a trick like
> NoChange_t. The drawback though is that it means even more overloads
> of conservativeResize.
>
> Benoit
>
> 2009/9/3 Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>:
>> Hi,
>>
>> just a short question regarding my recent commit for conservative
>> resizing. I added an option to allow the user to set the part by which
>> a matrix might be extended to zero - currently via a boolean.
>> Initially I wanted to offer the ability to pass the scalar value
>> explicity which lead to problems, in particular for integer matrices.
>>
>> My initial intended interface was somethink like:
>>
>> void conservativeResize(int,int) // matrices with uninitialized memory
>> void conservativeResize(int,int,Scalar value) // matrices with new
>> memory set to value
>> void conservativeResize(int) // vectors with uninitialized memory
>> void conservativeResize(int,Scalar value) // vectors with new memory set to zero
>>
>> Here, the last and first definitions obviously clash when Scalar is int.
>>
>> Do you have any proposal how to circumvent this problem. Do we need
>> the uninitialized version at all for conservativeResizing? Any use
>> case for this?
>>
>> - Hauke
>>
>>
>>
>
>
>