Task

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

using namespace std;

struct Vector {
    float x, y, z;
};
float norma(Vector X);

Vector gradient(Vector X);

float norma(Vector X) {
    return sqrt(pow(X.x,2)) + (pow(X.y,2)) + (pow(X.z,2));
}
Vector gradient(Vector X) {
    Vector grad;
    grad.x = 4*((pow(X.x,2))+2*X.y-3*X.z-0.9)*X.x+16*X.x-4*(pow(X.y,2))+4*X.z-24.84+12*X.y-4*(pow(X.z,2));
    grad.y = 4*(pow(X.x,2))+26*X.y-12*X.z-30.66-4*(2*X.x-(pow(X.y,2))+X.z-1.7)*X.y+12*X.x-6*(pow(X.z,2));
    grad.z = -6*(pow(X.x,2))-12*X.y+20*X.z+2.0+4*X.x-2*(pow(X.y,2))-4*(2*X.x+3*X.y-pow(X.z,2)-4.51)*X.z;

    return grad;
}
int main() {
    Vector X0, X1;
    float I = 0.001, eps = 0.0001, b = 0;

    X0.x = X0.y = X0.z = 0;
    X1.x = X1.y = X1.z = 0;

    while(norma(gradient(X1))>eps) {
        b++;
        if(b > 1) {
            X0 = X1;
        }
        X1.x = X0.x -I * gradient(X0).x;
        X1.y = X0.y -I * gradient(X0).y;
        X1.z = X0.z -I * gradient(X0).z;
    }
    cout << " Our roots are " << endl;
    cout << X1.x << endl <<  X1.y << endl << X1.z << endl;

    return 0;
}