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==Compute the sample standard deviation==

<source lang="cpp">
#include <algorithm>
#include <cmath>
#include <functional>
#include <iostream>
#include <list>
#include <numeric>
#include <vector>
using namespace std;
template <class T>
void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
}
int main( )
{
const float a[] = { 1, 1.3, 1.5};
vector<float> data( a,a + sizeof( a ) / sizeof( a[0] ) );
print( data );
float mean = accumulate( data.begin(), data.end(), 0.0f )/ data.size();
cout << mean;
vector<float> zero_mean( data );
transform( zero_mean.begin(), zero_mean.end(), zero_mean.begin(),bind2nd( minus<float>(), mean ) );
float deviation = inner_product( zero_mean.begin(),zero_mean.end(), zero_mean.begin(), 0.0f );
deviation = sqrt( deviation / ( data.size() - 1 ) );
cout << deviation;
}

</source>

==inner_product( ) produces a summation of the product of corresponding elements in two sequences and returns the result.==

<source lang="cpp">
#include <iostream>
#include <vector>
#include <numeric>
using namespace std;

int main()
{
vector<int> v1(5), v2(5);
int i, total;

for(i=0; i<5; i++)
v1[i] = i;
for(i=0; i<5; i++)
v2[i] = i+2;

total = inner_product(v1.begin(), v1.end(),v2.begin(), 0);

cout << total;

return 0;
}

</source>

==Use inner_product to calculate inner reverse product==

<source lang="cpp">

/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
using namespace std;
int main()
{
list<int> coll;
INSERT_ELEMENTS(coll,1,6);
PRINT_ELEMENTS(coll);
/* process sum of 1*6 ... 6*1
* (0 + 1*6 + 2*5 + 3*4 + 4*3 + 5*2 + 6*1)
*/
cout << "inner reverse product: "
<< inner_product (coll.begin(), coll.end(), // first range
coll.rbegin(), // second range
0) // initial value
<< endl;
}
/*
1 2 3 4 5 6
inner reverse product: 56
*/

</source>

==Use inner_product to process sum of all products(0 + 1*1 + 2*2 + 3*3 + 4*4 + 5*5 + 6*6)==

<source lang="cpp">

/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
using namespace std;
int main()
{
list<int> coll;
INSERT_ELEMENTS(coll,1,6);
PRINT_ELEMENTS(coll);
/* process sum of all products
* (0 + 1*1 + 2*2 + 3*3 + 4*4 + 5*5 + 6*6)
*/
cout << "inner product: "
<< inner_product (coll.begin(), coll.end(), // first range
coll.begin(), // second range
0) // initial value
<< endl;
}
/*
1 2 3 4 5 6
inner product: 91
*/

</source>

==Use inner_product with inner and outer operation==

<source lang="cpp">

/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
using namespace std;
int main()
{
list<int> coll;
INSERT_ELEMENTS(coll,1,6);
PRINT_ELEMENTS(coll);
/* process product of all sums
* (1 * 1+1 * 2+2 * 3+3 * 4+4 * 5+5 * 6+6)
*/
cout << "product of sums: "
<< inner_product (coll.begin(), coll.end(), // first range
coll.begin(), // second range
1, // initial value
multiplies<int>(), // inner operation
plus<int>()) // outer operation
<< endl;
}
/*
1 2 3 4 5 6
product of sums: 46080
*/

</source>

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