{

cout << "Example: Find scale (standard deviation)." << endl;

try

{

normal N01; // Default 'standard' normal distribution with zero mean

double sd = 1.; // and standard deviation is 1.

double z = -2.; // z to give prob p

double p = 0.001; // only 0.1% below z = -2

cout << "Normal distribution with mean = " << N01.location() // aka N01.mean()

<< ", standard deviation " << N01.scale() // aka N01.standard_deviation()

<< ", has " << "fraction <= " << z

<< ", p = " << cdf(N01, z) << endl;

cout << "Normal distribution with mean = " << N01.location()

<< ", standard deviation " << N01.scale()

<< ", has " << "fraction > " << z

<< ", p = " << cdf(complement(N01, z)) << endl; // Note: uses complement.

double l = N01.location();

double s = find_scale<normal>(z, p, l);

cout << "scale (standard deviation) = " << s << endl;

normal np001pc(N01.location(), s);

cout << "Normal distribution with mean = " << l

<< " has " << "fraction <= " << z

<< ", p = " << cdf(np001pc, z) << endl;

cout << "Normal distribution with mean = " << l

<< " has " << "fraction > " << z

<< ", p = " << cdf(complement(np001pc, z)) << endl;

using boost::math::policies::policy;

using boost::math::policies::domain_error;

using boost::math::policies::ignore_error;

typedef policy<domain_error<ignore_error> > ignore_domain_policy;

// find_scale with new policy, using typedef.

l = find_scale<normal>(z, p, l, ignore_domain_policy());

// Default policy policy<>, needs using boost::math::policies::policy;

l = find_scale<normal>(z, p, l, policy<>());

// Default policy, fully specified.

l = find_scale<normal>(z, p, l, boost::math::policies::policy<>());

// New policy, without typedef.

l = find_scale<normal>(z, p, l, policy<domain_error<ignore_error> >());

z = -2.;

double q = 0.999; // = 1 - p; // complement of 0.001.

sd = find_scale<normal>(complement(z, q, l));

normal np95pc(l, sd); // Same standard_deviation (scale) but with mean(scale) shifted

cout << "Normal distribution with mean = " << l << " has "

<< "fraction <= " << z << " = " << cdf(np95pc, z) << endl;

cout << "Normal distribution with mean = " << l << " has "

<< "fraction > " << z << " = " << cdf(complement(np95pc, z)) << endl;

}

catch(const std::exception& e)

{ // Always useful to include try & catch blocks because default policies

// are to throw exceptions on arguments that cause errors like underflow, overflow.

// Lacking try & catch blocks, the program will abort without a message below,

// which may give some helpful clues as to the cause of the exception.

std::cout <<

"\n""Message from thrown exception was:\n " << e.what() << std::endl;

}

return 0;