ec dif Toate

#include <stdio.h>
#include <conio.h>
#include <math.h>
#define N 50

double f (double a, double b)
{
    return a+b;
}

void EulerImb (double x0, double y0, double h, int n, double y[])
{
    double x[N];
    int i;

    printf("\n Euler imbunatatit:") ;
    y[0]=y0;
    x[0]=x0;
    for (i=1;i<=n;i++)
    {
        x[i]=x[0]+i*h;
        y[i]=y[i-1]+0.5*h*(f(x[i-1],y[i-1])+f(x[i],y[i-1]+h*f(x[i-1],y[i-1])));
        printf("\n calculat: %lf, verificare: %lf", y[i], 2*exp(x[i])-x[i]-1);
    }
    getch() ;
}

void EulerMod (double x0, double y0, double h, int n, double y[])
{
    double x[N];
    int i;

    printf("\n Euler modificat:") ;
    y[0]=y0;
    x[0]=x0;
    for (i=1;i<=n;i++)
    {
        x[i]=x[i-1]+h;
        y[i]=y[i-1]+h*(f(x[i-1]+0.5*h,y[i-1]+0.5*h*f(x[i-1],y[i-1])));
        printf("\n calculat: %lf, verificare: %lf", y[i], 2*exp(x[i])-x[i]-1);
    }
    getch() ;
}

void RungeKutta4(double x0, double y0, double h, int n, double y[])
{
    double x[N];
    int i;

    printf("\n RK 4:") ;
    x[0]=x0;
    y[0]=y0;
    for(i=1;i<=n;i++)
    {
        x[i]=x0+i*h;
        double k1=f(x[i-1],y[i-1]);
        double k2=f(x[i-1]+0.5*h,y[i]+0.5*h*k1);
        double k3=f(x[i-1]+0.5*h,y[i]+0.5*h*k2);
        double k4=f(x[i],y[i]+h*k3);
        y[i]=y[i-1]+(h/6)*(k1+2*k2+2*k3+k4);
        printf("\n calculat: %lf, verificare: %lf", y[i], 2*exp(x[i])-x[i]-1);
    }
    getch() ;
}


int main ()
{
  static double sol[N];
  double x0,y0,pas;
  int n,i;

  printf("Numarul de puncte in care se calculeaza solutia : ");
  scanf("%d",&n);
  printf("Abscisa punctului prin care trece graficul : (este 0, pt. verificare)");
  scanf("%lf",&x0);
  printf("Ordonata punctului prin care trece graficul : (este 1, pt. verificare)");
  scanf("%lf",&y0);
  printf("Pasul intre abscise : ");
  scanf("%lf",&pas);

  EulerImb (x0,y0,pas,n,sol);
  EulerMod (x0,y0,pas,n,sol);
  RungeKutta4(x0,y0,pas,n,sol);

  return 1;
}