ad_output.cpp

View page source

AD Output Operator: Example and Test

# include <cppad/cppad.hpp>

# include <sstream>  // std::ostringstream
# include <string>   // std::string
# include <iomanip>  // std::setprecision, setw, setfill, right

namespace {
    template <class S>
    void set_ostream(S &os)
    {   os
        << std::setprecision(4) // 4 digits of precision
        << std::setw(6)         // 6 characters per field
        << std::setfill(' ')    // fill with spaces
        << std::right;          // adjust value to the right
    }
}

bool ad_output(void)
{   bool ok = true;

    // This output stream is an ostringstream for testing purposes.
    // You can use << with other types of streams; i.e., std::cout.
    std::ostringstream stream;

    // output an AD<double> object
    CppAD::AD<double>  pi = 4. * atan(1.); // 3.1415926536
    set_ostream(stream);
    stream << pi;

    // output a VecAD<double>::reference object
    CppAD::VecAD<double> v(1);
    CppAD::AD<double> zero(0);
    v[zero]   = exp(1.);                  // 2.7182818285
    set_ostream(stream);
    stream << v[zero];

    // convert output from stream to string
    std::string str = stream.str();

    // check the output
    ok      &= (str == " 3.142 2.718");

    return ok;
}