#include
#include

float trapez( float a, float b, float(* function) (float x) , int n );
float test(float x);
float simpson( float a, float b, float (* function) (float x) , int n );

void main()
{

float ca, ct, cs, a, b, blad1, blad2;
int i, m, n;
FILE *plik=fopen("wynik.xls","w");

printf("podaj a i b\n");
scanf("%f%f",&a,&b);
printf("podaj m\n");
scanf("%d",&m);
ca=log(b)-log(a);
n=1;
for(i=1;i<=m;i++)
{n=n*2;
ct=trapez(a,b,test,n);
cs=simpson(a,b,test,n);
blad1 = fabs(ca-ct);
blad2 = fabs(ca-cs);
printf("ca=%f ct=%f blad1=%f \n",ca,ct,blad1);
fprintf(plik,"%d %f %f \n",n,blad1,blad2);
}
}

float trapez( float a, float b, float(* function) (float x) , int n )
{
float value;
/* Calkowanie metoda trapezow */
float h, x, sum;
int i;

h = (b - a) / (float) n; // krok calkowania

sum = 0.0;
for( i=1; i x = a + i * h;
sum += function(x);
}

value = ( function(a) + 2.0*sum + function(b) ) * h / 2.0;

return value;
}

float test(float x)
{
float fx;
fx=1./x;
return fx;
}

float simpson( float a, float b, float (* function) (float x) , int n )
{
float value;
/* Calkowanie metoda Simpsona */
float h, x, sum;
int i;
int nc; // oznaczenie dla liczby wezlow wewnetrznych

nc = abs( n / 2 ) * 2;
h = (b - a) / (float) nc; // krok calkowania

sum = 0.0;
for( i=1; i x = a + (float) i * h;
sum += 4.0*function(x) + 2.0*function(x+h);
}

value = ( function(a) + sum + 4.0*function(b-h) + function(b) ) * h / 3.0;

return value;
}