CLOG(3) Library Functions Manual CLOG(3)

clog clogf clogl — complex natural logarithm functions

#include <complex.h>

double complex clog(double complex z);
float complex clogf(float complex z);
long double complex clogl(long double complex z);

The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2024 defers to the ISO C standard.

These functions shall compute the complex natural (base ) logarithm of z, with a branch cut along the negative real axis.

These functions shall return the complex natural logarithm value, in the range of a strip mathematically unbounded along the real axis and in the interval [- i ℼ, + i ℼ] along the imaginary axis.

clog ( conj ( z)), clogf ( conjf ( z)), and clogl ( conjl ( z)) shall return exactly the same value as conj ( clog ( z)), conjf ( clogf ( z)), and conjl ( clogl ( z)), respectively, including for the special values of z below.

If z is -0 + i 0, -Inf + i ℼ shall be returned and the divide-by-zero floating-point exception shall be raised.

If z is +0 + i 0, -Inf + i 0 shall be returned and the divide-by-zero floating-point exception shall be raised.

If z is x + i Inf where x is finite, +Inf + i ℼ/2 shall be returned.

If z is x + i NaN where x is finite, NaN + i NaN shall be returned and the invalid floating-point exception may be raised.

If z is -Inf + iy where y is positive-signed and finite, +Inf + i ℼ shall be returned.

If z is +Inf + iy where y is positive-signed and finite, +Inf + i 0 shall be returned.

If z is -Inf + i Inf, +Inf + i 3ℼ/4 shall be returned.

If z is +Inf + i Inf, +Inf + i ℼ/4 shall be returned.

If z is ±Inf + i NaN, +Inf + i NaN shall be returned.

If z is NaN + iy where y is finite, NaN + i NaN shall be returned and the invalid floating-point exception may be raised.

If z is NaN + i Inf, +Inf + i NaN shall be returned.

If z is NaN + i NaN, NaN + i NaN shall be returned.

No errors are defined.

None.

None.

None.

None.

cexp(3)

XBD <complex.h>

First released in Issue 6. Derived from the ISO/IEC 9899:1999 (“ISO C99”) standard.

Austin Group Defect 1302 is applied, aligning these functions with the ISO/IEC 9899:2018 standard.

June 14, 2024 posix.fail