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  1. #include <iostream>
  2. #include <cmath>
  3. #include <iomanip>      // std::setprecision
  4.  
  5. double func(double x)
  6. {
  7. 	return x*cos(x)-2.0*cos(x)*cos(x)-2.0;
  8. }
  9.  
  10. double derive(double x)
  11. {
  12. 	return cos(x)-x*sin(x)+2.0*sin(2.0*x);
  13. }
  14.  
  15. int main()
  16. {
  17. 	double x=0.0; // initial x;
  18. 	double lastx=x-0.1;
  19. 	while(std::abs(x-lastx)>1e-10)
  20. 	{
  21. 		lastx=x;
  22. 		x-=func(x)/derive(x);
  23. 	}
  24. 	std::cout<<"final x="<<std::setprecision(16)<<x<<std::endl;
  25. 	return 0;
  26. }
Success #stdin #stdout 0s 3460KB
comments (?)
stdin 
Standard input is empty
stdout 
final x=5.200801328145019
https://ideone.com/Yx3j5r
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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