Проверить правильность циклического алг.

#include <iostream.h>
#include <math.h>
 
void main()
{float x,y,xn,xk,hx,yn,yk,hy,u;
cout <<"vvod xn,xk,hx,yn,yk,hy"<<endl;
cin >> xn>>xk>>hx>>yn>>yk>>hy;
x=xn;
while (x<=xk)
{ y=yn;
while (y<=yk)
{ if ((x-y)<=-1)
u=y*exp(x);
{if ((x-y)>=1)
u=x*x-exp(y);
else
u=log(pow(x,4)+1);
cout <<"x="<<x<<" y="<<y<<" u="<<u<<endl;
y=y+hy;}
x=x+hx;}
}
}

void main(){
  float x, y, xn, xk, hx, yn, yk, hy, u;
  cout << "vvod xn, xk, hx, yn, yk, hy" << endl;
  cin >> xn >> xk >> hx >> yn >> yk >> hy;
  x = xn;
  while ( x <= xk ){
      y = yn;
      while ( y <= yk ){
          if ( (x-y) <= -1 )
            u = y * exp(x);
          {if ( (x-y) >= 1 )
             u = x * x - exp(y);
          else
            u = log( pow(x,4) + 1 );
          cout << "x=" << x << " y=" << y << " u=" << u << endl;
          y = y + hy;}
          x = x + hx;
      }
  }
}

#include<iostream.h>
#include<math.h>
 
void main()
{double x,y,u,xn,xk,hx,yn,yk,hy;
cout<<"vvod xn,xk,hx,yn,yk,hy"<<endl;
cin>>xn>>xk>>hx>>yn>>yk>>hy;
for(x=xn;x<=xk;x=x+hx)
for(y=yn;y<=yk;y=y+hy)
{if((x-y)<=-1) u=y*exp(x);
else
if((x-y)<1) u=log((pow(x,4))+1);
else
u=pow(x,2)-exp(y);
cout<<"x="<<x<<" y="<<y<<" u="<<u<<"\n";
}
}

#include<iostream.h>
#include<math.h>
void main()
{double x,y,z,u,umin,xn,xk,hx,yn,yk,hy,zn,zk,hz;
cout<<"vvod xn,xk,hx,yn,yk,hy,zn,zk,hz"<<endl;
cin>>xn>>xk>>hx>>yn>>yk>>hy>>zn>>zk>>hz;
umin=1000;
for(x=xn;x<=xk;x=x+hx)
for(y=yn;y<=yk;y=y+hy)
for(z=zn;z<=zk;z=z+hz)
{if((u>0) && (u<umin))
u=-sqrt(pow(y,2)+(4*pow(x,2))/3)+5*((pow(cos(x*y),4)));
umin=u;
 cout<<"x="<<x<<" y="<<y<<"z="<<z<< " umin="<<umin<<"\n";
}
 }