std::setprecision(10)

This is a manipulator in C++ that sets the precision of floating-point numbers that are output to the console or a file. The argument passed to the setprecision function specifies the number of digits after the decimal point that should be displayed.

For example, if you have a floating-point number x and you want to display it with 10 digits after the decimal point, you would use the following code:

cout << setprecision(10) << x;

This would output the value of x with 10 digits after the decimal point.

Note that the setprecision function only affects the number of digits displayed, not the actual value of the number. If you need to perform calculations with high precision, you should use a library such as Boost or GMP.