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Complex Number (complex)

Single-precision floating-point complex number arithmetic for DSP.

Data Structure​

struct complex_t {
    float real;
    float imag;
};

API​

void complex_add(struct complex_t * z, struct complex_t * a, struct complex_t * b);
void complex_sub(struct complex_t * z, struct complex_t * a, struct complex_t * b);
void complex_mul(struct complex_t * z, struct complex_t * a, struct complex_t * b);
void complex_div(struct complex_t * z, struct complex_t * a, struct complex_t * b);
void complex_neg(struct complex_t * z, struct complex_t * a);
void complex_conj(struct complex_t * z, struct complex_t * a);
void complex_expj(struct complex_t * z, float phi);
void complex_proj(struct complex_t * z, struct complex_t * a);
void complex_normalize(struct complex_t * z, struct complex_t * a);
float complex_abs(struct complex_t * z);
float complex_arg(struct complex_t * z);
  • complex_add/sub/mul/div — Arithmetic operations, z = a op b
  • complex_neg — Negation, z = -a
  • complex_conj — Conjugate, z = a*
  • complex_expj — Rotation factor, z = exp(j * phi)
  • complex_proj — Projection onto the Riemann sphere
  • complex_normalize — Normalize to unit complex number
  • complex_abs — Magnitude, |z|
  • complex_arg — Phase angle, arg(z) in radians

Example​

Complex Multiplication​

struct complex_t a = { 1.0f, 2.0f };
struct complex_t b = { 3.0f, 4.0f };
struct complex_t z;

complex_mul(&z, &a, &b);

Rotation Factor​

struct complex_t z;
complex_expj(&z, 3.14159265f / 4.0f);

Magnitude and Phase​

struct complex_t a = { 3.0f, 4.0f };
float r = complex_abs(&a);
float theta = complex_arg(&a);