function template
<valarray>
std::log
template<class T> valarray<T> log (const valarray<T>& x);
Compute natural logarithm of valarray elements
Returns a valarray containing the natural logarithm (base-e logarithm) of all the elements of x, in the same order.
The function calls log (unqualified) once for each element.
This function overloads cmath's log.
Parameters
- x
- valarray containing elements of a type for which the unary function log is defined.
Return value
A valarray object with the natural logarithms of the elements of x.
Example
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// log valarray example
#include <iostream> // std::cout
#include <cstddef> // std::size_t
#include <cmath> // std::log(double)
#include <valarray> // std::valarray, std::log(valarray)
int main ()
{
double val[] = {5.0, 6.6, 8.0, 9.9};
std::valarray<double> foo (val,4);
std::valarray<double> bar = log (foo);
std::cout << "foo:";
for (std::size_t i=0; i<foo.size(); ++i)
std::cout << ' ' << foo[i];
std::cout << '\n';
std::cout << "bar:";
for (std::size_t i=0; i<bar.size(); ++i)
std::cout << ' ' << bar[i];
std::cout << '\n';
return 0;
}
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Output:
foo: 5 6.6 8 9.9
bar: 1.60944 1.88707 2.07944 2.29253
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See also
- log (cmath)
- Compute natural logarithm (function
)
- log10
- Compute common logarithm of valarray elements (function template
)
- exp
- Compute exponential of valarray elements (function template
)
- pow
- Compute power of valarray elements (function template
)