// integrall.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include "string.h"
#include "math.h"
//#include "Winbase.h"
using namespace std;
//typedef char* (*td_integral) (int,int,float,float (*f)(float));
typedef float (*td_func)(float);
typedef float (*td_metd)(int,int,float,td_func);

//#include <conio.h>
void show_menu(char mod, int arg1)
{
switch(mod)
{
case 'a':
printf(" \n");
printf("Welcome to Integral calculation programm! \n");
printf("Here some actions you can choose below: \n\n");
printf("==Avaliable calculation functions==\n");
printf("-----------------------------------\n");
printf("1) x+3 \n");
printf("2) x^2 + 5x - 1 \n");
printf("-----------------------------------\n");
printf("Your choise ");
break;
case 'b':
printf("You have selected %d - one function. \n",arg1);
printf("Now enter integral range to function count from 'a' to 'b' \n");
break;
}
}
float func1(float x)
{
return x+3;
}
float func2(float x)
{
return x*x + 5*x - 1;
}

float trapeci (int a,int b,float n,td_func f) // func (*f) (func)
{
float h,x,summ1,summ2,rez;
h=(b-a)/n;
int i;
summ1 = f(a)+f(a+n*h);
summ2 = 0;
for (i=1; i<= n -1; i++)
{
x = a+i*h;
summ2 += f(a+i*h);
}
summ2 *= 2;
rez = 0.5 * h * (summ1 + summ2);
return rez;
}

float simpson (int a, int b, float n, td_func f)
{float h,rez,x;
float summ1=0;
float summ2=0;
float summ3=0;
h = (b-a)/(6*n);

int i;
summ1 = (*f)(0)+(*f)(b);
for (i=1; i<= 2*n-1; i+=2)
{
x = a+((b-a)*i)/(2*n);
summ2 += (*f)(x);
}
for (i=2; i<= 2*n-2; i+=2)
{
x = a+((b-a)*i)/(2*n);
summ3 += (*f)(x);
}

rez = (h)*(summ1+4*summ2+2*summ3);
return rez;
}

float doubleculc(int a, int b,float epsi, td_func func,td_metd metod)//float (*metod)(int, int, float,td_func func))
{
float n = 10;
float I2N,IN;
do
{
IN = metod(a,b,n,func);//integral_trapeciei(a,b,n,func);//simpson(a,b,n,func);
I2N =metod(a,b,2*n,func); //integral_trapeciei(a,b,2*n,func);//simpson(a,b,2*n,func);
n = n*2;
}
while (abs((I2N - IN))>epsi);

return IN;
}

int _tmain()
{
int number;
int a,b;
float epsi,IN;
float (*func)(float);
float (*metod)(int, int, float,float (*f)(float));
int repeate = 0;

do
{

show_menu('a',0);
scanf("%d",&number);
switch(number)
{
case 1: func = &func1; break;
case 2: func = &func2; break;
}
do
{
system("cls");
show_menu('b',number);
scanf("%d",&a);
scanf("%d",&b);
if(a>b){printf("A must be low than B");}
}while(a>b);
system("cls");

metod = &trapeci;
printf("-----------TRAPECI----------\n");
printf("Epsi = 0.1 "); epsi = 0.1;
IN = doubleculc(a,b,epsi,func,metod);
printf(" %f\n",IN);

printf("Epsi = 0.01 "); epsi = 0.01;
IN = doubleculc(a,b,epsi,func,metod);
printf(" %f\n",IN);

printf("Epsi = 0.001 "); epsi = 0.001;
IN = doubleculc(a,b,epsi,func,metod);
printf(" %f\n",IN);

printf("Epsi = 0.00001 "); epsi = 0.00001;
IN = doubleculc(a,b,epsi,func,metod);
printf(" %f\n",IN);

metod = &simpson;
printf("-----------SIMPSON----------\n");
printf("Epsi = 0.1 "); epsi = 0.1;
IN = doubleculc(a,b,epsi,func,metod);
printf(" %f\n",IN);

printf("Epsi = 0.01 "); epsi = 0.01;
IN = doubleculc(a,b,epsi,func,metod);
printf(" %f\n",IN);

printf("Epsi = 0.001 "); epsi = 0.001;
IN = doubleculc(a,b,epsi,func,metod);
printf(" %f\n",IN);

printf("Epsi = 0.00001 "); epsi = 0.00001;
IN = doubleculc(a,b,epsi,func,metod);
printf(" %f\n",IN);

printf("----------------------------\n");

printf("Repeate? ");
scanf("%d",&repeate);
}while(repeate);
return 0;
}