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[Bug?] Vector view

From: Huynh, Hoai Nam
Subject: [Bug?] Vector view
Date: Wed, 25 Mar 2020 20:19:50 +0000



   Would you please answer the question below regarding gsl_vector_view_array() 

Using the GSL (GNU Scientific Library), I'm trying to understand why 
gsl_vector_view_array() returns a slighly modified value after assignment.

In the code below, I declare a vector_view 'qview_test' which is linked to 
table q_test[0]=0.0 and display its value which is 0.0. Then, I change the 
value of q_test[0]=1.12348 and expecting the same value for qview_test, but it 
gets alterated to qview_test=1.1234800000000000341771055900608189.

How do you explain such a result ? How to replicate the result without GSL (for 
ex. with Matlab) ?

#include <iostream>
#include <gsl/gsl_blas.h>
using namespace std;

double q_test[1]={0.0};
gsl_vector_view qview_test;

int nb_variable = 1;

int main()


    cout << "qview before: " << gsl_vector_get(&qview_test.vector,0)<< endl;

    // Assign value

    cout << "qview after: " << gsl_vector_get(&qview_test.vector,0) << endl;

    return 0;


Best regards,

Dr. Hoai Nam HUYNH

Postdoctoral fellow

The University of British Columbia

Department of Mechanical Engineering

Manufacturing Automation Laboratory

2366 Main Mall (ICICS Room 091)

Vancouver BC V6T 1Z4 Canada

Phone: +1 604-827-4370


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Description: Test_View.cpp

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