алгоритм наискорейшего спуска

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#include <conio>
#include <vcl.h>
#include <math.h>
#include <iostream>
#pragma hdrstop

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

#pragma argsused
int main(int argc, char* argv[])
{
  using namespace std;
  cout << "f(x)=(x1-2)^4+(x1-2x2)^2" << endl;
  double x11 = 0.5;
  double x12 = 1;
  cout << "x1=[" << x11 << ";" << x12 << "]" << endl;
  double a = 4*pow(x11-2,3)-2*(x11-2*x12);
  double b = 4*(x11-2*x12);
  double f = pow(x11-2,4)+pow(x11-2*x12,2);
  double df = sqrt(pow(a,2) + pow(b,2));

  double x21, x22, lym, lym_buf;
  bool fnd = false;
  double lim = 0.0001;
  cout << endl;

  while (true) {
    lym = 0.1;
    lym_buf = lym;

    while (lym>lim) {
      x21 = x11 - lym*(a/df);
      x22 = x12 - lym*(b/df);
      double f2 = pow(x21-2,4)+pow(x21-2*x22,2);
      cout << lym << " - " << f << " - " << f2 << " df: " << df << endl;
      if (f2>=f) lym /= 4;
      else {
        lym_buf = lym;
        lym *= 2;
        fnd = true;
        f = f2;
      }
    }
    cout << endl;
    if (fnd) {
      fnd = false;
      lym = lym_buf;
      x11 = x11 - lym*(a/df);
      x12 = x12 - lym*(b/df);
      f = pow(x11-2,4)+pow(x11-2*x12,2);

      a = 4*pow(x11-2,3)-2*(x11-2*x12);
      b = 4*(x11-2*x12);
      df = sqrt(pow(a,2) + pow(b,2));
    }
    else break;
  }

  cout << endl << "Min:" << x11 << "," << x12 << " - " << pow(x11-2,4)+pow(x11-2*x12,2) << " - lym_buf: " << lym_buf<< endl;
  getch();
  return 0;
}
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