ceph/src/boost/libs/units/example/tutorial.cpp

   1 // Boost.Units - A C++ library for zero-overhead dimensional analysis and
   2 // unit/quantity manipulation and conversion
   3 //
   4 // Copyright (C) 2003-2008 Matthias Christian Schabel
   5 // Copyright (C) 2008 Steven Watanabe
   6 //
   7 // Distributed under the Boost Software License, Version 1.0. (See
   8 // accompanying file LICENSE_1_0.txt or copy at
   9 // http://www.boost.org/LICENSE_1_0.txt)
  10
  11 /**
  12 \file tutorial.cpp
  13
  14 \brief Basic tutorial using SI units.
  15
  16 \details
  17 Tutorial
  18 Defines a function that computes the work, in joules,
  19 done by exerting a force in newtons over a specified distance
  20 in meters and outputs the result to std::cout.
  21
  22 Also code for computing the complex impedance
  23 using std::complex<double> as the value type.
  24
  25 Output:
  26 @verbatim
  27 //[tutorial_output
  28 F  = 2 N
  29 dx = 2 m
  30 E  = 4 J
  31
  32 V   = (12.5,0) V
  33 I   = (3,4) A
  34 Z   = (1.5,-2) Ohm
  35 I*Z = (12.5,0) V
  36 I*Z == V? true
  37 //]
  38 @endverbatim
  39 */
  40
  41 //[tutorial_code
  42 #include <complex>
  43 #include <iostream>
  44
  45 #include <boost/typeof/std/complex.hpp>
  46
  47 #include <boost/units/systems/si/energy.hpp>
  48 #include <boost/units/systems/si/force.hpp>
  49 #include <boost/units/systems/si/length.hpp>
  50 #include <boost/units/systems/si/electric_potential.hpp>
  51 #include <boost/units/systems/si/current.hpp>
  52 #include <boost/units/systems/si/resistance.hpp>
  53 #include <boost/units/systems/si/io.hpp>
  54
  55 using namespace boost::units;
  56 using namespace boost::units::si;
  57
  58 quantity<energy>
  59 work(const quantity<force>& F, const quantity<length>& dx)
  60 {
  61     return F * dx; // Defines the relation: work = force * distance.
  62 }
  63
  64 int main()
  65 {
  66     /// Test calculation of work.
  67     quantity<force>     F(2.0 * newton); // Define a quantity of force.
  68     quantity<length>    dx(2.0 * meter); // and a distance,
  69     quantity<energy>    E(work(F,dx));  // and calculate the work done.
  70
  71     std::cout << "F  = " << F << std::endl
  72               << "dx = " << dx << std::endl
  73               << "E  = " << E << std::endl
  74               << std::endl;
  75
  76     /// Test and check complex quantities.
  77     typedef std::complex<double> complex_type; // double real and imaginary parts.
  78
  79     // Define some complex electrical quantities.
  80     quantity<electric_potential, complex_type> v = complex_type(12.5, 0.0) * volts;
  81     quantity<current, complex_type>            i = complex_type(3.0, 4.0) * amperes;
  82     quantity<resistance, complex_type>         z = complex_type(1.5, -2.0) * ohms;
  83
  84     std::cout << "V   = " << v << std::endl
  85               << "I   = " << i << std::endl
  86               << "Z   = " << z << std::endl
  87               // Calculate from Ohm's law voltage = current * resistance.
  88               << "I * Z = " << i * z << std::endl
  89               // Check defined V is equal to calculated.
  90               << "I * Z == V? " << std::boolalpha << (i * z == v) << std::endl
  91               << std::endl;
  92     return 0;
  93 }
  94 //]