clog(), clogf(), clogl()
Compute the complex natural (base-e) logarithm of a complex number
Synopsis:
#include <complex.h>
double complex clog(double complex z );
float complex clogf(float complex z );
long double complex clogl(long double complex z );
Arguments:
- z
- The complex value that you want to compute the complex natural logarithm of.
Library:
- libm
- The general-purpose math library.
- libm-sve
- A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.
Your system requirements will determine how you should work with these libraries:
- If you want only selected processes to run with the SVE version, you can include both libraries in your OS image and use the -l m or -l m-sve option to qcc to link explicitly against the appropriate one.
- If you want all processes to use the SVE version, include libm-sve.so in your OS image and set up a symbolic link from libm.so to libm-sve.so. Use the -l m option to qcc to link against the library.
Description:
These functions compute the complex natural (base-e) logarithm of the complex number specified by z with a branch cut along the negative real axis. The natural logarithm of a complex number z with polar coordinate components (r,θ) equals ln r + i(θ+2nπ), with the principal value ln r + iθ.
To check for error situations, use feclearexcept() and fetestexcept(). For example:
- Call
feclearexcept(FE_ALL_EXCEPT)before calling clog(), clogf(), or clogl(). - On return, if
fetestexcept(FE_ALL_EXCEPT)is nonzero, then an error has occurred.
Returns:
If no errors occur, the complex natural logarithm of z, in the range of a strip in the interval [−iπ, +iπ] along the imaginary axis and mathematically unbounded along the real axis.
| If z is: | These functions return: | Errors: |
|---|---|---|
| -0 + 0i | -Inf + πi | FE_DIVBYZERO |
| 0 + 0i | -Inf + 0i | FE_DIVBYZERO |
| x + Infi, for any finite x | Inf + (π/2)i | — |
| x + NaNi, for any finite x | NaN + NaNi | — |
| -Inf + yi, for any finite positive y | -Inf + πi | — |
| Inf + yi, for any finite positive y | -Inf + 0i | — |
| -Inf + Infi | Inf + (3π/4)i | — |
| Inf + Infi | Inf + (π/4)i | — |
| ±Inf + NaNi | Inf + NaNi | — |
| NaN + yi, for any finite y | NaN + NaNi | — |
| NaN + Infi | NaN + NaNi | — |
| NaN + NaNi | NaN + NaNi | — |
These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.
Classification:
| Safety: | |
|---|---|
| Cancellation point | No |
| Signal handler | Yes |
| Thread | Yes |