Problem with the sqrt function

when I use the sqrt function to find the sqrt of a determinant of a complex matrix, sometimes matlab changes the sign of the real and imaginary part of the square root. for example if the it is -x+iy the sqrt function gives the answer as x-iy How do I get around this?

[Adam]

Just like in the real case, if a is a square root then so is -a. In the real case the positive square root is always returned, for complex numbers the documentation states that sqrt(z) returns:

sqrt(r)*(cos(phi/2) + 1i*sin(phi/2))

where r = abs(z) is the radius and phi = angle(z) is the phase angle on the closed interval -pi <= phi <= pi.

[Stephen23]

"Problem with the sqrt function"

What is the problem? sqrt is giving a correct output.