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example_a11c
n_thread
repeat
size
automatic
,
dynamic thread adjustment is used.
Otherwise, n_thread must be a positive number
specifying the number of OpenMP threads to use.
automatic
,
the number of times to repeat the calculation of the number of zeros
in total interval is automatically determined.
In this case, the rate of execution of the total solution is reported.
If the argument repeat is not equal to automatic,
it must be a positive integer.
In this case repeat determination of the number of times
the calculation of the zeros in the total interval is repeated.
The rate of execution is not reported (it is assumed that the
program execution time is being calculated some other way).
# ifdef _OPENMP
# include <omp.h>
# endif
# include <cmath>
# include <cstring>
# include <cstdlib>
// see http://www.coin-or.org/CppAD/Doc/cppad_vector.htm
# include <cppad/vector.hpp>
// see http://www.coin-or.org/CppAD/Doc/speed_test.htm
# include <cppad/speed_test.hpp>
// Beginning of Example A.1.1.1c of OpenMP 2.5 standard document ---------
void a1(int n, float *a, float *b)
{ int i;
# ifdef _OPENMP
# pragma omp parallel for
# endif
for(i = 1; i < n; i++) /* i is private by default */
b[i] = (a[i] + a[i-1]) / 2.0;
}
// End of Example A.1.1.1c of OpenMP 2.5 standard document ---------------
// routine that is called to repeat the example a number of times
void test(size_t size, size_t repeat)
{ // setup
size_t i;
float *a = new float[size];
float *b = new float[size];
for(i = 0; i < size; i++)
a[i] = float(i);
int n = int(size);
// run test
for(i = 0; i < repeat; i++)
a1(n, a, b);
// tear down
delete [] a;
delete [] b;
return;
}
// main program
int main(int argc, char *argv[])
{
using std::cout;
using std::endl;
// get command line arguments -----------------------------------
char *usage = "example_a11c n_thread repeat size";
if( argc != 4 )
{ std::cerr << usage << endl;
exit(1);
}
argv++;
// n_thread
int n_thread;
if( std::strcmp(*argv, "automatic") == 0 )
n_thread = 0;
else n_thread = std::atoi(*argv);
argv++;
// repeat
size_t repeat;
if( std::strcmp(*argv, "automatic") == 0 )
repeat = 0;
else
{ assert( std::atoi(*argv) > 0 );
repeat = std::atoi(*argv);
}
argv++;
// size
assert( std::atoi(*argv) > 1 );
size_t size = std::atoi(*argv++);
// ---------------------------------------------------------------
// minimum time for test (repeat until this much time)
double time_min = 1.;
# ifdef _OPENMP
if( n_thread > 0 )
{ omp_set_dynamic(0); // off dynamic thread adjust
omp_set_num_threads(n_thread); // set the number of threads
}
// now determine the maximum number of threads
n_thread = omp_get_max_threads();
assert( n_thread > 0 );
// inform the user of the maximum number of threads
cout << "OpenMP: version = " << _OPENMP;
cout << ", max number of threads = " << n_thread << endl;
# else
cout << "_OPENMP is not defined, ";
cout << "running in single tread mode" << endl;
n_thread = 1;
# endif
// Correctness check (store result in ok)
size_t i;
float *a = new float[size];
float *b = new float[size];
for(i = 0; i < size; i++)
a[i] = float(i);
int n = size;
a1(n, a, b);
bool ok = true;
for(i = 1; i < size ; i++)
ok &= std::fabs( 2. * b[i] - a[i] - a[i-1] ) <= 1e-6;
delete [] a;
delete [] b;
if( repeat > 0 )
{ // user specified the number of times to repeat the test
test(size, repeat);
}
else
{ // automatic determination of number of times to repeat test
// speed test uses a SimpleVector with size_t elements
CppAD::vector<size_t> size_vec(1);
size_vec[0] = size;
CppAD::vector<size_t> rate_vec =
CppAD::speed_test(test, size_vec, time_min);
// report results
cout << "size = " << size_vec[0] << endl;
cout << "repeats per sec = " << rate_vec[0] << endl;
}
if( ok )
cout << "Correctness Test Passed" << endl;
else cout << "Correctness Test Failed" << endl;
return static_cast<int>( ! ok );
}