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// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-or-later
// SPDX-FileCopyrightText: Bradley M. Bell <bradbell@seanet.com>
// SPDX-FileContributor: 2003-22 Bradley M. Bell
// ----------------------------------------------------------------------------
/*
{xrst_begin a11c_openmp.cpp}
A Simple OpenMP Example and Test
################################
Purpose
*******
This example just demonstrates OpenMP and does not use CppAD at all.
Source Code
***********
{xrst_literal
// BEGIN C++
// END C++
}
{xrst_end a11c_openmp.cpp}
----------------------------------------------------------------------------
*/
// BEGIN C++
# include <omp.h>
# include <limits>
# include <cmath>
# include <cassert>
// for size_t
# include <cstddef>
//
# define NUMBER_THREADS 4
namespace {
// Beginning of Example A.1.1.1c of OpenMP 2.5 standard document ---------
void a1(int n, float *a, float *b)
{ // Original had 'int i;' instead of 'int i = 0;'
// Silence warning by clang 9.0.0: variable 'i' is uninitialized.
int i = 0;
# pragma omp parallel for
for(i = 1; i < n; i++) /* i is private by default */
{ assert( omp_get_num_threads() == NUMBER_THREADS );
b[i] = (a[i] + a[i-1]) / float(2);
}
}
// End of Example A.1.1.1c of OpenMP 2.5 standard document ---------------
}
bool a11c(void)
{ bool ok = true;
// Test setup
size_t i, n = 1000;
float *a = new float[n];
float *b = new float[n];
for(i = 0; i < n; i++)
a[i] = float(i);
int n_thread = NUMBER_THREADS; // number of threads in parallel regions
omp_set_dynamic(0); // off dynamic thread adjust
omp_set_num_threads(n_thread); // set the number of threads
a1(int(n), a, b);
// check the result
float eps = float(100) * std::numeric_limits<float>::epsilon();
for(i = 1; i < n ; i++)
ok &= std::fabs( (float(2) * b[i] - a[i] - a[i-1]) / b[i] ) <= eps;
delete [] a;
delete [] b;
return ok;
}
// END C++
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