function template

std::log

<valarray>
template<class T> valarray<T> log (const valarray<T>& x);
Compute natural logarithm of valarray elements
Returns a valarray object containing the natural logarithm (base-e logarithm) of all the elements of x.

This function overloads cmath's log function.

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>
#include <cmath>
#include <valarray>
using namespace std;

int main ()
{
  double val[] = {5.0, 6.6, 8.0, 9.9};
  valarray<double> foo (val,4);

  valarray<double> bar = log (foo);

  cout << "foo: ";
  for (size_t i=0; i<foo.size(); ++i)
	  cout << foo[i] << ' ';
  cout << endl;

  cout << "bar: ";
  for (size_t i=0; i<bar.size(); ++i)
	  cout << bar[i] << ' ';
  cout << endl;

  return 0;
}


Output:

foo: 5 6.6 8 9.9
bar: 1.60944 1.88707 2.07944 2.29253

See also