Trouble compiling code

Hi, I´m new to OpenGL and am trying to compile and run a code I got from a textbook (Interactive Computer Graphics: A Top-Down Approach with Shader-Based OpenGL (6th Edition)). I use Xcode 3.2.6 and OpenGl 3.0. The code i want to compile is:

Code :

// Two-Dimensional Sierpinski Gasket       
// Generated using randomly selected vertices and bisection
#include "Angel.h"
const int NumPoints = 5000;
//----------------------------------------------------------------------------
 
void
init( void )
{
    vec2 points[NumPoints];
 
    // Specifiy the vertices for a triangle
    vec2 vertices[3] = {
        vec2( -1.0, -1.0 ), vec2( 0.0, 1.0 ), vec2( 1.0, -1.0 )
    };
 
    // Select an arbitrary initial point inside of the triangle
    points[0] = vec2( 0.25, 0.50 );
 
    // compute and store N-1 new points
    for ( int i = 1; i < NumPoints; ++i ) {
        int j = rand() % 3;   // pick a vertex at random
 
        // Compute the point halfway between the selected vertex
        //   and the previous point
        points[i] = ( points[i - 1] + vertices[j] ) / 2.0;
    }
 
    // Create a vertex array object
    GLuint vao[1];
    glGenVertexArraysAPPLE( 1, vao );
    glBindVertexArrayAPPLE( vao[0] );
 
 
    // Create and initialize a buffer object
    GLuint buffer;
    glGenBuffers( 1, &buffer );
    glBindBuffer( GL_ARRAY_BUFFER, buffer );
    glBufferData( GL_ARRAY_BUFFER, sizeof(points), points, GL_STATIC_DRAW );
 
    // Load shaders and use the resulting shader program
    GLuint program = InitShader( "vshader_a2.glsl", "fshader_a2.glsl" );
    glUseProgram( program );
 
    // Initialize the vertex position attribute from the vertex shader
    GLuint loc = glGetAttribLocation( program, "vPosition" );
    glEnableVertexAttribArray( loc );
    glVertexAttribPointer( loc, 2, GL_FLOAT, GL_FALSE, 0,
						  BUFFER_OFFSET(0) );
 
    glClearColor( 1.0, 1.0, 1.0, 1.0 ); // white background
}
 
//----------------------------------------------------------------------------
 
void
display( void )
{
    glClear( GL_COLOR_BUFFER_BIT );     // clear the window
    glDrawArrays( GL_POINTS, 0, NumPoints );    // draw the points
    glFlush();
}
 
//----------------------------------------------------------------------------
 
void
keyboard( unsigned char key, int x, int y )
{
    switch ( key ) {
		case 033:
			exit( EXIT_SUCCESS );
			break;
    }
}
 
//----------------------------------------------------------------------------
 
int
main( int argc, char **argv )
{
    glutInit( &argc, argv );
    glutInitDisplayMode( GLUT_RGBA );
    glutInitWindowSize( 512, 512 );
 
    glutCreateWindow( "Sierpinski Gasket" );
 
    init();
 
    glutDisplayFunc( display );
    glutKeyboardFunc( keyboard );
 
    glutMainLoop();
    return 0;
}

and the header file Angle:

Code :

//////////////////////////////////////////////////////////////////////////////
//
//  --- Angel.h ---
//
//   The main header file for all examples from Angel 6th Edition
//
//////////////////////////////////////////////////////////////////////////////
 
#ifndef __ANGEL_H__
#define __ANGEL_H__
 
//----------------------------------------------------------------------------
// 
// --- Include system headers ---
//
 
#include <cmath>
#include <iostream>
 
//  Define M_PI in the case it's not defined in the math header file
#ifndef M_PI
#  define M_PI  3.14159265358979323846
#endif
 
//----------------------------------------------------------------------------
//
// --- Include OpenGL header files and helpers ---
//
//   The location of these files vary by operating system.  We've included
//     copies of open-soruce project headers in the "GL" directory local
//     this this "include" directory.
//
 
// Rowan: Alas, OS X GLUT won't work with GLSL 1.50 anyway.
 
#ifdef __APPLE__  // include Mac OS X verions of headers
#  include <OpenGL/OpenGL.h>
#  include <GLUT/glut.h>
#else // non-Mac OS X operating systems
 
// Without glew, define glewInit to do nothing
//#  include <GL/glew.h>
#  define glewInit(x)
 
#  define GL_GLEXT_PROTOTYPES
#  include <GL/gl.h>
#  include <GL/glext.h>
#  include <GL/freeglut.h>
#  include <GL/freeglut_ext.h>
 
#endif  // __APPLE__
 
 
 
// Define a helpful macro for handling offsets into buffer objects
#define BUFFER_OFFSET( offset )   ((GLvoid*) (offset))
 
//----------------------------------------------------------------------------
//
//  --- Include our class libraries and constants ---
//
 
namespace Angel {
 
//  Helper function to load vertex and fragment shader files
GLuint InitShader( const char* vertexShaderFile,
		   const char* fragmentShaderFile );
 
//  Defined constant for when numbers are too small to be used in the
//    denominator of a division operation.  This is only used if the
//    DEBUG macro is defined.
const GLfloat  DivideByZeroTolerance = GLfloat(1.0e-07);
 
//  Degrees-to-radians constant 
const GLfloat  DegreesToRadians = M_PI / 180.0;
 
}  // namespace Angel
 
#include "vec.h"
#include "mat.h"
#include "CheckError.h"
 
#define Print(x)  do { std::cerr << #x " = " << (x) << std::endl; } while(0)
 
//  Globally use our namespace in our example programs.
using namespace Angel;
 
#endif // __ANGEL_H__

I get the following error:
Undefined symbols:
"Angel::InitShader(char const*, char const*)", referenced from:
init() in main.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

I don´t know how I can fix this problem so any help would be really appreciated.