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Projections, Conjugates, and Decomposing of Complex Numbers

ISO C99 also defines functions that perform basic operations on complex numbers, such as decomposition and conjugation. The prototypes for all these functions are in complex.h. All functions are available in three variants, one for each of the three complex types.

double creal (complex double z) Function
float crealf (complex float z) Function
long double creall (complex long double z) Function
These functions return the real part of the complex number z.

double cimag (complex double z) Function
float cimagf (complex float z) Function
long double cimagl (complex long double z) Function
These functions return the imaginary part of the complex number z.

complex double conj (complex double z) Function
complex float conjf (complex float z) Function
complex long double conjl (complex long double z) Function
These functions return the conjugate value of the complex number z. The conjugate of a complex number has the same real part and a negated imaginary part. In other words, conj(a + bi) = a + -bi.

double carg (complex double z) Function
float cargf (complex float z) Function
long double cargl (complex long double z) Function
These functions return the argument of the complex number z. The argument of a complex number is the angle in the complex plane between the positive real axis and a line passing through zero and the number. This angle is measured in the usual fashion and ranges from 0 to 2π.

carg has a branch cut along the positive real axis.

complex double cproj (complex double z) Function
complex float cprojf (complex float z) Function
complex long double cprojl (complex long double z) Function
These functions return the projection of the complex value z onto the Riemann sphere. Values with a infinite imaginary part are projected to positive infinity on the real axis, even if the real part is NaN. If the real part is infinite, the result is equivalent to
INFINITY + I * copysign (0.0, cimag (z))