the analysis toolpak has some routines for working with complex numbers I
believe.
for example:
the Complex function
and
IMABS Returns the absolute value (modulus) of a complex number
IMAGINARY Returns the imaginary coefficient of a complex number
IMARGUMENT Returns the argument theta, an angle expressed in radians
IMCONJUGATE Returns the complex conjugate of a complex number
IMCOS Returns the cosine of a complex number
IMDIV Returns the quotient of two complex numbers
IMEXP Returns the exponential of a complex number
IMLN Returns the natural logarithm of a complex number
IMLOG10 Returns the base-10 logarithm of a complex number
IMLOG2 Returns the base-2 logarithm of a complex number
IMPOWER Returns a complex number raised to an integer power
IMPRODUCT Returns the product of two complex numbers
IMREAL Returns the real coefficient of a complex number
IMSIN Returns the sine of a complex number
IMSQRT Returns the square root of a complex number
IMSUB Returns the difference of two complex numbers
IMSUM Returns the sum of complex numbers