Cumulative standard deviation: Difference between revisions

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#include <numeric>

template <typename Iterator>

~~double~~ ~~standard_dev(~~ std::vector<double> ~~& )~~ ;

double standard_dev( Iterator begin , Iterator end ) {

double mean = std::accumulate( begin , end , 0 ) / std::distance( begin , end ) ;

std::vector<double> squares ;

for( Iterator vdi = begin ; vdi != end ; vdi++ )

squares.push_back( std::pow( *vdi - mean , 2 ) ) ;

return std::sqrt( std::accumulate( squares.begin( ) , squares.end( ) , 0 ) / squares.size( ) ) ;

}

int main( ) {

double demoset[] = { 2 , 4 , 4 , 4 , 5, 5 , 7 , 9 } ;

double demoset[] = { 2 , 4 , 4 , 4 , 5 , 5 , 7 , 9 } ;

int demosize = sizeof demoset / sizeof *demoset ;

std::vector<double> numbers ;

for ( double *d = demoset ; d != demoset + demosize ; ++d )

numbers.push_back( *d ) ;

std::cout << "The standard deviation of\n" ;

std::copy( ~~numbers.begin( )~~ , ~~numbers.end(~~ ) , std::ostream_iterator<double>( std::cout, " " ) ) ;

std::copy( demoset , demoset + demosize , std::ostream_iterator<double>( std::cout, " " ) ) ;

std::cout << "\nis " << standard_dev( ~~numbers~~ ) << " !\n" ;

std::cout << "\nis " << standard_dev( demoset , demoset + demosize ) << " !\n" ;

return 0 ;

}

double standard_dev( ~~std::vector<double>~~ & ~~numbers~~ ) {

double mean = std::accumulate( ~~numbers.~~begin~~( )~~ , ~~numbers.~~end~~( )~~ , 0 ) / ~~numbers.size~~( ) ;

std::vector<double> squares ;

for( ~~std::vector<double>::const_iterator~~ vdi = ~~numbers.~~begin~~( )~~ ; vdi != ~~numbers.~~end~~( )~~ ; vdi++ )

squares.push_back( pow( *vdi - mean , 2 ) ) ;

return ~~pow~~( std::accumulate( squares.begin( ) , squares.end( ) , 0 ) / squares.size( ) ~~, 0.5~~ ) ;

}</lang>