# <valarray>

**[<valarray>](https://en.cppreference.com/w/cpp/header/valarray)** provides `std::valarray<T>`, a vector-like container optimized for mathematical operations: elementwise operations, slicing, and masking. Most scientific code uses Eigen or NumPy instead.

`valarray` has an odd API and is rarely used in practice.

## Example

This example performs elementwise addition on two valarrays, demonstrating the vectorized operations this container provides.

```cpp
// compile: g++ -std=c++11 -o valarrayexample valarrayexample.cpp
// run: ./valarrayexample
// description: elementwise valarray operations

#include <valarray>
#include <iostream>

int main() {
    std::valarray<int> a{1, 2, 3};
    std::valarray<int> b{4, 5, 6};
    
    std::valarray<int> c = a + b;
    
    std::cout << "sum: ";
    for (int x : c) std::cout << x << " ";
    std::cout << "\n";
    
    return 0;
}
```