текст программы следующий:

#include <conio.h>
#include <iostream.h>
#include <math.h>

//---------------------------------------------------------------------------

#pragma hdrstop

//---------------------------------------------------------------------------


class X
{
public:
X();
~X();
void init(double x, double y, double z);

friend void print(X * a);
friend void run(X * a);
private:
double x;
double y;
double z;

double result;
};

X::X()
{
}

X::~X()
{
}

void X::init(double x, double y, double z)
{
this->x = x;
this->y = y;
this->z = z;
}

void print(X * a)
{
cout << "x = " << a->x << ", ";
cout << "y = " << a->y << ", ";
cout << "z = " << a->z << ", ";
cout << "result = " << a->result << "\n";
}

void run(X * a)
{
double x = a->x;
double y = a->y;
double z = a->z;

a->result = Ln(pow(y,-pow(fabs(x),1/2))*(x-y/2)+pow(sin(arctg(z)),2);
}

#pragma argsused
void main()
{
X * a = new X();
a->init(1.825e2, 18.225, -3.298e-2);
run(a);
print(a);
delete a;
getch();
}
//---------------------------------------------------------------------------
ВЫДАЁТ ОШИБКУ В СТРОКЕ:
a->result = Ln(pow(y,-pow(fabs(x),1/2))*(x-y/2)+pow(sin(arctg(z)),2);
ОШИБКИ СЛЕД:
Неизвестная функция ln, arctg