operator+,-,*,/,%,&,|,^,<<,>>,&&,|| std::valarray
Defined in header
<valarray>
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template <class T> std::valarray<T> operator+ (const std::valarray<T>& lhs, const std::valarray<T>& rhs);
template <class T> std::valarray<T> operator- (const std::valarray<T>& lhs, const std::valarray<T>& rhs); |
(1) | |
template <class T> std::valarray<T> operator+ (const T& val, const std::valarray<T>& rhs);
template <class T> std::valarray<T> operator- (const T& val, const std::valarray<T>& rhs); |
(2) | |
template <class T> std::valarray<T> operator+ (const std::valarray<T>& lhs, const T& rhs);
template <class T> std::valarray<T> operator- (const std::valarray<T>& lhs, const T& val); |
(3) | |
Apply binary operators to each element of two valarrays, or a valarray and a value.
Contents |
[edit] Parameters
rhs | - | a numeric array |
lhs | - | a numeric array |
val | - | a value of type T
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[edit] Return value
A valarray with the same size as the parameter.
[edit] Note
The behaviour is undefined when the two arguments are valarrays with different sizes.
The function can be implemented with the return type different from std::valarray. In this case, the replacement type has the following properties:
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- All const member functions of std::valarray are provided.
- std::valarray, std::slice_array, std::gslice_array, std::mask_array and std::indirect_array can be constructed from the replacement type.
- All functions accepting an argument of type const std::valarray& except begin() and end() (since C++14) should also accept the replacement type.
- All functions accepting two arguments of type const std::valarray& should accept every combination of const std::valarray& and the replacement type.
- The return type does not add more than two levels of template nesting over the most deeply-nested argument type.
[edit] Example
Finds real roots of multiple quadratic equations.
#include <valarray> #include <iostream> int main() { std::valarray<double> a(1, 8); std::valarray<double> b{1, 2, 3, 4, 5, 6, 7, 8}; std::valarray<double> c = -b; // literals must also be of type T (double in this case) std::valarray<double> d = std::sqrt((b * b - 4.0 * a * c)); std::valarray<double> x1 = (-b - d) / (2.0 * a); std::valarray<double> x2 = (-b + d) / (2.0 * a); std::cout << "quadratic equation root 1, root 2" << "\n"; for (size_t i = 0; i < a.size(); ++i) { std::cout << a[i] << "x\u00B2 + " << b[i] << "x + " << c[i] << " = 0 "; std::cout << x1[i] << ", " << x2[i] << "\n"; } }
Output:
quadratic equation root 1, root 2 1x² + 1x + -1 = 0 -1.61803, 0.618034 1x² + 2x + -2 = 0 -2.73205, 0.732051 1x² + 3x + -3 = 0 -3.79129, 0.791288 1x² + 4x + -4 = 0 -4.82843, 0.828427 1x² + 5x + -5 = 0 -5.8541, 0.854102 1x² + 6x + -6 = 0 -6.87298, 0.872983 1x² + 7x + -7 = 0 -7.88748, 0.887482 1x² + 8x + -8 = 0 -8.89898, 0.898979