# Basic usageΒΆ

Initialize a 2-D array and compute the sum of one of its rows and a 1-D array.

```#include <iostream>
#include "xtensor/xarray.hpp"
#include "xtensor/xio.hpp"

xt::xarray<double> arr1
{{1.0, 2.0, 3.0},
{2.0, 5.0, 7.0},
{2.0, 5.0, 7.0}};

xt::xarray<double> arr2
{5.0, 6.0, 7.0};

xt::xarray<double> res = xt::view(arr1, 1) + arr2;

std::cout << res;
```

Outputs:

```{7, 11, 14}
```

Initialize a 1-D array and reshape it inplace.

```#include <iostream>
#include "xtensor/xarray.hpp"
#include "xtensor/xio.hpp"

xt::xarray<int> arr
{1, 2, 3, 4, 5, 6, 7, 8, 9};

arr.reshape({3, 3});

std::cout << arr;
```

Outputs:

```{{1, 2, 3},
{4, 5, 6},
{7, 8, 9}}
```

```#include <iostream>
#include "xtensor/xarray.hpp"
#include "xtensor/xmath.hpp"
#include "xtensor/xio.hpp"

xt::xarray<double> arr1
{1.0, 2.0, 3.0};

xt::xarray<unsigned int> arr2
{4, 5, 6, 7};

arr2.reshape({4, 1});

xt::xarray<double> res = xt::pow(arr1, arr2);

std::cout << res;
```

Outputs:

```{{1, 16, 81},
{1, 32, 243},
{1, 64, 729},
{1, 128, 2187}}
```