[تنبيه - عنوان غير مناسب : ]يا شباب ممكن مساعدة

sallam alikom , sorry but my computer doesn't support arabic letters

I have an assignment to find the first derivative of a function . . .

this is my work ,but I think I have a logic error since it compiled perfectly without errors

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#ifndef f1_h

#define f1_h

double deriv(int x , double dx);

#endif

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#include "f1.h"

double deriv(int x ,double dx )

{

return (x+dx)-(x)/dx;

}

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#include <iostream>

#include "f1.h"

#include "f2.h"

using namespace std;

int main()

{

int x;

const double dx=0.000001;

cout<<"enter your function :\n";

cin>>x;

deriv( x , dx );

print( x , dx );

return 0;

}

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#ifndef f2_h

#define f2_h

void print(int x ,double dx);

#endif

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#include "f2.h"

#include <iostream>

using namespace std;

void print(int x ,double dx)

{

cout<<"f'(x) = "<<((x+dx)-(x))/dx<<endl;

}