Lesson of 20 July 2009 (afternoon)

Skeleton of a Simple vector/matrix library for 3d vector and 3x3 matrix (C++ style)

File lib3d.hh

  1/*
  2  File: lib3d.hh
  3  Simple vector/matrix library for 3d vector and 3x3 matrix.
  4*/
  5
  6/* first trick, avoid double inclusion using conditional compilation */
  7
  8/* check if LIB3D_H is defined, if NOT the lines up to #endif are expanded */
  9#ifndef LIB3D_HH
 10#define LIB3D_HH // define an empty macro, only to define the symbol LIB3D_HH
 11
 12#include <iostream>
 13
 14// valueType is the "real number" type
 15typedef double valueType ;
 16
 17// A vector is a CLASS with 3 field, x y z
 18class point3d {
 19private:
 20  valueType x ;
 21  valueType y ;
 22  valueType z ;
 23public:
 24  valueType *ptr ;
 25private:
 26private:
 27private:
 28public:
 29  // constructor
 30  point3d() {
 31    std::cout << "pass to constructor 1\n" ;
 32    x=y=z=0 ;
 33    ptr = new valueType[100] ; 
 34  }
 35
 36  point3d( valueType x, valueType y, valueType z ) {
 37    std::cout << "pass to constructor 2\n" ;
 38    this -> x = x ;
 39    this -> y = y ;
 40    this -> z = z ;
 41    ptr = new valueType[10] ; 
 42  }
 43  
 44  ~point3d() {
 45    delete [] ptr ;
 46    std::cout << "pass to destructor\n" ;
 47  }
 48
 49  point3d const &
 50  operator = ( point3d const & in ) ;
 51
 52  void
 53  setup( valueType x, valueType y, valueType z ) ;
 54
 55  valueType getx() const { return x ; } // const means that the method
 56                                        // do not modify the class
 57
 58  valueType gety() const { return y ; }
 59  valueType getz() const { return z ; }
 60} ;
 61
 62std::ostream & // return a reference (pointer) to the object
 63               // ostream is into the namespace std
 64operator << ( std::ostream & s, // left argumenet of left << right
 65              point3d const & v ) ; // right argumenet of left << right
 66
 67
 68point3d scal( valueType s, point3d const & v ) ;
 69
 70point3d
 71add( point3d const & v1, 
 72     point3d const & v2 ) ;
 73
 74point3d
 75sub( point3d const & v1, 
 76     point3d const & v2 ) ;
 77
 78point3d
 79vector_product( point3d const & v1, 
 80                point3d const & v2 ) ;
 81
 82valueType dot( point3d const & v1, point3d const & v2 ) ;
 83
 84// Use external operator
 85inline
 86point3d
 87operator ^ ( point3d const & a, point3d const & b ) 
 88{ return vector_product( a, b ) ; }
 89
 90inline
 91valueType
 92operator * ( point3d const & a, point3d const & b ) 
 93{ return dot( a, b ) ; }
 94
 95
 96// matrix 3 by 3 type
 97class matrix3d {
 98  valueType m[3][3] ;
 99} ;
100
101#endif /* close LIB3D_HH */

File lib3d.cc

  1/*
  2  File: lib3d.c
  3  Simple vector/matrix library for 3d vector and 3x3 matrix.
  4*/
  5
  6#include "lib3d.hh"
  7
  8// define the copy opersator = for class point3d
  9point3d const &
 10point3d::operator = ( point3d const & in ) {
 11  std::cout << "pass to copy operator\n" ;
 12  this -> x = in . x ;
 13  this -> y = in . y ;
 14  this -> z = in . z ;
 15}
 16
 17// define the method setup of class point3d
 18void
 19point3d::setup( valueType x, valueType y, valueType z ) {
 20  this -> x = x ;
 21  this -> y = y ;
 22  this -> z = z ;
 23}
 24
 25std::ostream & // return a reference (pointer) to the object
 26               // ostream is into the namespace std
 27operator << ( std::ostream & s, // left argumenet of left << right
 28              point3d const & v ) { // right argumenet of left << right
 29  s << "[ " << v.getx() << " , " << v.gety() << " , " << v.getz() << " ]" ;
 30  return s ;
 31}
 32
 33point3d
 34scal( valueType s, point3d const & v ) {
 35  valueType x = v . getx() * s ;
 36  valueType y = v . gety() * s ;
 37  valueType z = v . getz() * s ;
 38  //point3d res( x, y, z ) ;
 39  //return res ;
 40  return point3d(x, y, z) ;
 41}
 42
 43point3d
 44add( point3d const & v1, 
 45     point3d const & v2 ) {
 46  return point3d( v1 . getx() + v2 . getx(),
 47                  v1 . gety() + v2 . gety(),
 48                  v1 . getz() + v2 . getz() ) ;
 49}
 50
 51point3d
 52sub( point3d const & v1, 
 53     point3d const & v2 ) {
 54  return point3d( v1 . getx() - v2 . getx(),
 55                  v1 . gety() - v2 . gety(),
 56                  v1 . getz() - v2 . getz() ) ;
 57}
 58
 59point3d
 60vector_product( point3d const & v1, 
 61                point3d const & v2 ) {
 62  return point3d( v1 . gety() * v2 . getz() - v1 . getz() * v2 . gety(),
 63                  v1 . getz() * v2 . getx() - v1 . getx() * v2 . getz(),
 64                  v1 . getx() * v2 . gety() - v1 . gety() * v2 . getx() ) ;
 65}
 66
 67valueType
 68dot( point3d const & v1, 
 69     point3d const & v2 ) {
 70  return v1 . getx() * v2 . getx() +
 71         v1 . gety() * v2 . gety() +
 72         v1 . getz() * v2 . getz() ;
 73}
 74
 75/*
 76void
 77l3d_zero_matrix( matrix3d m ) {
 78  m[0][0] = m[0][1] = m[0][2] =
 79  m[1][0] = m[1][1] = m[1][2] =
 80  m[2][0] = m[2][1] = m[2][2] = 0 ;
 81}
 82
 83void
 84l3d_id_matrix( matrix3d m ) {
 85  m[0][1] = m[0][2] = m[1][0] =
 86  m[1][2] = m[2][0] = m[2][1] = 0 ;
 87  m[0][0] = m[1][1] = m[2][2] = 1 ;
 88}
 89
 90void
 91l3d_ones_matrix( matrix3d m ) {
 92  m[0][0] = m[0][1] = m[0][2] =
 93  m[1][0] = m[1][1] = m[1][2] =
 94  m[2][0] = m[2][1] = m[2][2] = 1 ;
 95}
 96
 97void
 98l3d_mv( matrix3d m, 
 99        point3d  const * v,
100        point3d        * pRes ) {
101  valueType tmp1 = m[0][0] * v -> x + m[0][1] * v -> y + m[0][2] * v -> z ;
102  valueType tmp2 = m[1][0] * v -> x + m[1][1] * v -> y + m[1][2] * v -> z ; 
103  pRes -> z      = m[2][0] * v -> x + m[2][1] * v -> y + m[2][2] * v -> z ; 
104  pRes -> y      = tmp2 ;
105  pRes -> x      = tmp1 ;
106}
107*/

File test.cc

 1#include "lib3d.hh"
 2#include <cmath>
 3
 4using namespace std ;
 5
 6int
 7main() {
 8
 9  cout << "begin program\n" ;
10  point3d  a, b, c ;
11  cout << "v1 and v2 defined and instanced\n" ;
12  matrix3d M ;
13  cout << "M and instanced\n" ;
14
15  a . setup( 1, sqrt(3.0), 0 ) ;
16  b . setup( 0.1, 1, 0 ) ;
17  c . setup( 0, 1, 2.1 ) ;
18  
19  cout << "Volume = " << dot( vector_product(a,b), c ) << '\n' ;
20  cout << "Volume = " << (a^b)*c << '\n' ;
21  
22  a = b ;
23  // is equivalent
24  a . operator = ( b ) ;
25  
26  operator * ( (operator ^(a,b)), c ) ;
27  
28//  add( v1, v2, v3 ) ;
29//  sub( v1, v2, v3 ) ;
30// vector_product( v1, v2, v3 ) ;
31
32  cout << "before point3d v3 = scal( 3, a ) \n" ;
33  point3d v3 = scal( 3, a ) ;
34  cout << "after point3d v3 = scal( 3, a ) \n" ;
35  
36  std::cout << "V3 = " << v3 << '\n' ;
37
38  return 0 ;
39}