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// Copyright 2015-2018 Hans Dembinski
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt
// or copy at http://www.boost.org/LICENSE_1_0.txt)
//[ guide_histogram_operators
#include <boost/histogram.hpp>
#include <cassert>
#include <vector>
int main() {
using namespace boost::histogram;
// make two histograms
auto h1 = make_histogram(axis::regular<>(2, -1.0, 1.0));
auto h2 = make_histogram(axis::regular<>(2, -1.0, 1.0));
h1(-0.5); // counts are: 1 0
h2(0.5); // counts are: 0 1
// add them
auto h3 = h1;
h3 += h2; // counts are: 1 1
// adding multiple histograms at once is likely to be optimized by the compiler so that
// superfluous temporaries avoided, but no guarantees are given; use this equivalent
// code when you want to make sure: h4 = h1; h4 += h2; h4 += h3;
auto h4 = h1 + h2 + h3; // counts are: 2 2
assert(h4.at(0) == 2 && h4.at(1) == 2);
// multiply by number, h4 *= 2 also works
auto h5 = h4 * 2; // counts are: 4 4
// divide by number; s4 /= 4 also works
auto h6 = h5 / 4; // counts are: 1 1
assert(h6.at(0) == 1 && h6.at(1) == 1);
assert(h6 != h5 && h5 == 4 * h6);
// note the special effect of multiplication on weight_storage
auto h = make_histogram_with(weight_storage(), axis::regular<>(2, -1.0, 1.0));
h(-0.5);
// counts are: 1 0
assert(h.at(0).value() == 1 && h.at(1).value() == 0);
auto h_sum = h + h;
auto h_mul = 2 * h;
// values are the same as expected...
assert(h_sum.at(0).value() == h_mul.at(0).value());
// ... but variances differ
assert(h_sum.at(0).variance() == 2 && h_mul.at(0).variance() == 4);
// equality operator checks variances, so histograms are not equal
assert(h_sum != h_mul);
}
//]
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