benchmarks/pi.cpp
/*******************************************************
*
* The complete license agreement can be obtained at:
********************************************************/
/*
monte-carlo estimation of PI
algorithm:
- generate random (x,y) samples uniformly
- count what percent fell inside (top quarter) of unit circle
*/
#include <arrayfire.h>
#include <math.h>
#include <stdio.h>
#include <cstdlib>
using namespace af;
// generate millions of random samples
static int samples = 20e6;
/* Self-contained code to run host and device estimates of PI. Note that
each is generating its own random values, so the estimates of PI
will differ. */
static double pi_device() {
array x = randu(samples, f32), y = randu(samples, f32);
return 4.0 * sum<float>(sqrt(x * x + y * y) < 1) / samples;
}
static double pi_host() {
int count = 0;
for (int i = 0; i < samples; ++i) {
float x = float(rand()) / RAND_MAX;
float y = float(rand()) / RAND_MAX;
if (sqrt(x * x + y * y) < 1) count++;
}
return 4.0 * count / samples;
}
// void wrappers for timeit()
static void device_wrapper() { pi_device(); }
static void host_wrapper() { pi_host(); }
int main(int argc, char** argv) {
try {
int device = argc > 1 ? atoi(argv[1]) : 0;
setDevice(device);
info();
printf("device: %.5f seconds to estimate pi = %.5f\n",
timeit(device_wrapper), pi_device());
printf(" host: %.5f seconds to estimate pi = %.5f\n",
timeit(host_wrapper), pi_host());
} catch (exception& e) {
fprintf(stderr, "%s\n", e.what());
throw;
}
return 0;
}
af::info
AFAPI void info()
af::setDevice
AFAPI void setDevice(const int device)
Sets the current device.
af::array
A multi dimensional data container.
Definition: array.h:35
af
Definition: algorithm.h:15
af::timeit
AFAPI double timeit(void(*fn)())
af::count
AFAPI array count(const array &in, const int dim=-1)
C++ Interface for counting non-zero values in an array.
af::sqrt
AFAPI array sqrt(const array &in)
C++ Interface for square root of input.
af::randu
AFAPI array randu(const dim4 &dims, const dtype ty, randomEngine &r)
af::exception
An ArrayFire exception class.
Definition: exception.h:29
arrayfire.h
af::exception::what
virtual const char * what() const
Returns an error message for the exception in a string format.
Definition: exception.h:60
f32
@ f32
32-bit floating point values
Definition: defines.h:211