# Big vector problem

**URL:** <https://www.ruby-forum.com/t/big-vector-problem/207909>\
**Category:** GNU Radio\
**Created:** [June 6, 2011, 9:38am UTC](https://www.ruby-forum.com/t/big-vector-problem/207909 "2011-06-06T09:38:13Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\
**Post date:** [June 6, 2011, 9:38am UTC](https://www.ruby-forum.com/t/big-vector-problem/207909/1 "2011-06-06T09:38:13Z")

</div>

Hi all

I have a problem with a big vector. The input/output of my entity is  
like:  
: gr\_block (“sub\_channel\_vff”,  
gr\_make\_io\_signature2 (2, 2, sizeof (float)\*3072, sizeof  
(char)),  
gr\_make\_io\_signature2 (1, 2, sizeof (float)\*5376))

And my forecast is like:  
ninput\_items\_required[i] = 76/4;

The problem is that one input Frame has a size about 76\*3072= 233472  
values and I cut four parts (at different positions) of size 5376 out of  
it.  
If I run the simulation I get an error:  
…is requesting more input data than we can provide.  
ninput\_items\_required = 19  
max\_possible\_items\_available = 4…

If I reduce the ninput\_items\_required value the simulation works, but  
the value reflectes not the truth and in the gr\_block file is written:  
“The estimate doesn’t have to be exact, but should be close”. Knows  
anybody a solution or a detour to work with this big vectors?

Any idea? Any help will be appreciated

Thanks  
Michael

---

<div class="post-metadata">

**Author:** ![SSMichael\_HSSinSS\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7feea3/32.png) [@SSMichael\_HSSinSS\_S](https://www.ruby-forum.com/u/SSMichael_HSSinSS_S)\
**Post date:** [June 6, 2011, 10:29am UTC](https://www.ruby-forum.com/t/big-vector-problem/207909/2 "2011-06-06T10:29:31Z")

</div>

On Mon, Jun 06, 2011 at 09:33:52AM +0200, Michael Höin wrote:

> ninput\_items\_required[i] = 76/4;  
> the value reflectes not the truth and in the gr\_block file is written:  
> “The estimate doesn’t have to be exact, but should be close”. Knows  
> anybody a solution or a detour to work with this big vectors?
> 
> Any idea? Any help will be appreciated

Hi Michael,

without knowing what you’re block’s supposed to do, two solutions come  
to mind:

1. You re-think the functionality of the block. Does it really need  
these massive input vectors?

2. You re-write the block to operate on streams. This should not be a  
problem since you’ve already chosen a gr\_block instead of a  
gr\_sync\_block. You might need some internal buffers (that operate  
outside the buffers provided by GNU Radio) and some state variables to  
remember where you are in the stream.  
Are you simply cutting stuff out of a stream? In that case, a re-write  
should be fairly simple.

MB

–  
Karlsruhe Institute of Technology (KIT)  
Communications Engineering Lab (CEL)

Dipl.-Ing. Martin B.  
Research Associate

Kaiserstraße 12  
Building 05.01  
76131 Karlsruhe

Phone: +49 721 608-43790  
Fax: +49 721 608-46071  
www.cel.kit.edu

KIT – University of the State of Baden-Württemberg and  
National Laboratory of the Helmholtz Association

---

<div class="post-metadata">

**Author:** ![SSMichael\_HSSinSS\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/7feea3/32.png) [@SSMichael\_HSSinSS\_S](https://www.ruby-forum.com/u/SSMichael_HSSinSS_S)\
**Post date:** [June 6, 2011, 1:28pm UTC](https://www.ruby-forum.com/t/big-vector-problem/207909/3 "2011-06-06T13:28:51Z")

</div>

Hi Martin

1. With this big vectors the code is very easy to read, because the  
standard has the same blocksizes.

2. Yes, a streamconvertion is a possible solution.

I also think about dummy data vectors to get a lower forecast value. Is  
this a good idea?

Thanks Michael