clog, clogf, clogl

Article
06/05/2017

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Retrieves the natural logarithm of a complex number, with a branch cut along the negative real axis.

Syntax

_Dcomplex clog(   
   _Dcomplex z   
);  
_Fcomplex clog(   
   _Fcomplex z   
);  // C++ only  
_Lcomplex clog(   
   _Lcomplex z   
);  // C++ only  
_Fcomplex clogf(   
   _Fcomplex z   
);  
_Lcomplex clogl(   
   _Lcomplex z   
);

Parameters

z
The base of the logarithm.

Return Value

The natural logarithm of z. The result is unbounded along the real axis and in the interval [−iπ, +iπ] along the imaginary axis.

The possible return values are:

z parameter	Return value
Positive	The base 10 logarithm of z
Zero	- ∞
Negative	NaN
NaN	NaN
+ ∞	+ ∞

Remarks

Because C++ allows overloading, you can call overloads of clog that take and return _Fcomplex and _Lcomplex values. In a C program, clog always takes and returns a _Dcomplex value.

Requirements

Routine	C header	C++ header
`clog`, `clogf`, `clogl`	<complex.h>	<ccomplex>

For more compatibility information, see Compatibility in the Introduction.