[C con Clase] ayuda codigo c++

[ivan ardila]

Buenas tardes me pueden hacer el favor y me colaboran con este error RungeKutta4V2.C:37:8: error: expected unqualified-id before numeric constant
RungeKutta4V2.C:44:8: error: expected unqualified-id before numeric constant

este es el codigo

/* From: "COMPUTATIONAL PHYSICS, 2nd Ed" 
   by RH Landau, MJ Paez, and CC Bordeianu 
   Copyright Wiley-VCH, 2007.
   Electronic Materials copyright: R Landau, Oregon State Univ, 2007;
   MJ Paez, Univ Antioquia, 2007; & CC Bordeianu, Univ Bucharest, 2007
   Support by National Science Foundation
*/
//  Edwin Munevar
//  RungeKutta4.C: 4th order Runge-Kutta solution adapted for any kind of acceleration      
       
#include <stdio.h>
#include<iostream>
#include<math.h>

#define N       2   // number of equations: y(t) and v(t)
#define dist    0.1 // stepsize
#define MIN     0.0 // minimum x
#define MAX   200.0 // maximum x
#define b1      0.5 //F=-b1*v
#define a1      0.2 //F=-a1*v*v
#define muc     0.5
#define mue     0.8
#define fN      9.8
#define k       1.0
#define m       1.0
#define Damping 0   //Choose the type of damping
#define om      3
#define mu      0.5
using namespace std;


//-------------------
//Global variables
double omega2 = k/m;
double gb1= b1/m;
double ga1= a1/m;
double mu = 0.5;

//-------------------
//Functions
void runge4(double, double* , double, double); 
double f(double, double*, double, int);
double Damp(double*, double);
double mu = (double *);

//--------------------------------------
main(){
  //Declaration of variables;
  double t=0.0, y[N], a;
  double yant, yact;
  double Et, Ec, Ep;
  	
  //Save data in Runge4.dat
  FILE *output;                               
  output= fopen("Runge4.dat","w");
  
  y[0]= 1.0;// initial position         
  y[1]= 0.0;// initial velocity          
  
  //Damping .......
  a = Damp(y, t);
  fprintf(output, "%f\t%f\t%f\t%f\n", t, y[0], y[1], a);
  
  for (t= MIN; t <=  MAX ; t += dist){
    yant = y[1];
    runge4(t, y, dist, a);
    yact = y[1];
    //Damping......
    a = Damp(y,t);
    fprintf(output, "%f\t%f\t%f\t%f\n", t, y[0], y[1], a);        
  }
  printf("data stored in Runge4.dat\n");
  fclose(output);
} //End of main program


//------------------------------------------------------
//Runge-Kutta function
void runge4(double t, double y[], double step, double a)  {    // rk subroutine
  double f(double t, double y[], double a, int i);
  double Dt = step/2.0,                                // the midpoint
  yt1[N], yt2[N], yt3[N], k1[N], k2[N], k3[N],k4[N];  // for Runge-Kutta
  int i;
  for (i = 0; i<N; i++){
    k1[i] = f(t, y, a, i);
    yt1[i]= y[i]+0.5*(k1[i]*step);
  }
  for (i = 0; i<N; i++){
    //Damping.....
    a = Damp(yt1,t);
    k2[i] = f(t+Dt, yt1, a, i); 
    yt2[i]= y[i]+0.5*(k2[i]*step);
  }
  for (i = 0; i<N; i++){
    //Damping.....
    a = Damp(yt2,t);
    k3[i] = f(t+Dt, yt2, a, i);
    yt3[i]= y[i]+(k3[i]*step);
  }
  for (i = 0; i<N; i++){
    //Damping....
    a = Damp(yt3,t);
    k4[i]= f(t + step, yt3, a, i);
  }

  for (i = 0; i<N; i++) 
    y[i] += (k1[i]+2*k2[i]+2*k3[i]+k4[i])*step/6.0;  //Runge-Kutta 4th order
} 


//---------------------------------------------
double f(double t, double y[], double a, int i) {// RHS function                      
  if (i ==  0) return(y[1]);                     // RHS of first equation
  if (i ==  1) return(a);                    // RHS of second equation
}


//---------------------------------------------
//Damping functions
double Damp(double yf[],double t){
  
  double res;
  //F=0
  if(Damping == 0)   
    res= -mu*yf[1]*(yf[0]*yf[0] - 1);

  //F=-bv                               
  else if(Damping == 1) 
    res= -omega2*yf[0]-gb1*yf[1];                    
  //F=-b*v*v
  else if(Damping == 2){ 
    if(yf[1] >= 0.0)                                 
      res= -omega2*yf[0]-ga1*yf[1]*yf[1];
    else
      res= -omega2*yf[0]+ga1*yf[1]*yf[1];
  }
  //F = -muc*N
  else if(Damping == 3){ 
    if(yf[1] >= 0.0)                                 
      res= -omega2*yf[0]-muc*fN;
    else
      res= -omega2*yf[0]+muc*fN;}
  else{
    cout << "Unknown damping" << endl;
    return -1;}
  
  return res;
}


Muchas gracias