Defined in header <valarray> | ||
---|---|---|
template< class T > valarray<T> sqrt( const valarray<T>& va ); |
For each element in va
computes the square root of the value of the element.
Parameters
va | - | value array to apply the operation to |
Return value
Value array containing square roots of the values in va
.
Notes
Unqualified function (sqrt
) is used to perform the computation. If such function is not available, std::sqrt
is used due to argument dependent lookup.
The function can be implemented with the return type different from std::valarray
. In this case, the replacement type has the following properties:
- All
const
member functions ofstd::valarray
are provided. -
std::valarray
,std::slice_array
,std::gslice_array
,std::mask_array
andstd::indirect_array
can be constructed from the replacement type. - All functions accepting an argument of type
const std::valarray&
exceptbegin()
andend()
(since C++14) should also accept the replacement type. - All functions accepting two arguments of type
const std::valarray&
should accept every combination ofconst 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.
Possible implementation
template<class T> valarray<T> sqrt(const valarray<T>& va) { valarray<T> other = va; for (T &i : other) { i = sqrt(i); } return other; } |
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
See also
applies the function std::pow to two valarrays or a valarray and a value (function template) | |
computes square root (√x) (function) | |
complex square root in the range of the right half-plane (function template) |
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