# Multiplicative constant vector for multiply\_const\_vcc

**URL:** <https://www.ruby-forum.com/t/multiplicative-constant-vector-for-multiply-const-vcc/242031>\
**Category:** GNU Radio\
**Created:** [May 21, 2015, 2:14pm UTC](https://www.ruby-forum.com/t/multiplicative-constant-vector-for-multiply-const-vcc/242031 "2015-05-21T14:14:24Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [May 21, 2015, 2:14pm UTC](https://www.ruby-forum.com/t/multiplicative-constant-vector-for-multiply-const-vcc/242031/1 "2015-05-21T14:14:24Z")

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Hi,

What is the proper way to set-up the multiplicative constant vector for  
multiply\_const\_vcc?

I tried the code below and although it compiles, upon running the  
program I  
get the following error:

_Segmentation fault (core dumped)._

The code:

std::vector\<gr\_complex\> k;  
k[0]=0.1;

blocks::multiply\_const\_vcc::sptr multiply\_const\_0 =  
blocks::multiply\_const\_vcc::make(k);

I’ll appreciate your help.

Thank you.

Best regards,  
Khalid

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**Author:** ![khalide](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/3bc359/32.png) [@khalide](https://www.ruby-forum.com/u/khalide)\
**Post date:** [May 22, 2015, 12:46am UTC](https://www.ruby-forum.com/t/multiplicative-constant-vector-for-multiply-const-vcc/242031/2 "2015-05-22T00:46:31Z")

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I think this might simply be a matter of out-of-boundary access on std::  
vector. You don’t set a size on your vector at creation, so it might  
have zero elements, of which you try to set the first by doing k[0].  
That means you access memory that is not yet there, I.e. a segmentation  
fault. Try k.push\_back!

Best regards,  
Marcus

Am 21. Mai 2015 14:13:16 MESZ, schrieb “khalid.el-darymli”  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):