CONJG(Z) returns the conjugate of Z. If Z is (x, y) then the result is (x, -y) 
Fortran 77 and later, has an overload that is a GNU extension
Elemental function
Z = CONJG(Z) 
| Z | The type shall be COMPLEX. | 
The return value is of type COMPLEX. 
program test_conjg
    complex :: z = (2.0, 3.0)
    complex(8) :: dz = (2.71_8, -3.14_8)
    z= conjg(z)
    print *, z
    dz = dconjg(dz)
    print *, dz
end program test_conjg
| Name | Argument | Return type | Standard | 
| DCONJG(Z) | COMPLEX(8) Z | COMPLEX(8) | GNU extension | 
    © Free Software Foundation
Licensed under the GNU Free Documentation License, Version 1.3.
    https://gcc.gnu.org/onlinedocs/gcc-10.2.0/gfortran/CONJG.html