FunctionNatural logarithm
Syntax C/C++#include <VFmath.h>
int VF_log( fVector Y, fVector X, ui size );
int VFx_log( fVector Y, fVector X, ui size, float A, float B, float C );
int VPF_logtoC( cfVector Y, pfVector X, ui size );
C++ VecObj#include <OptiVec.h>
int vector<T>::log( const vector<T>& X );
int vector<T>::x_log( const vector<T>& X, const T& A, const T& B, const T& C );
int vector<complex<T>>::logtoC( const vector<polar<T>>& X );
Pascal/Delphiuses VFmath;
function VF_log( Y, X:fVector; size:UIntSize ): IntBool;
function VFx_log( Y, X:fVector; size:UIntSize; A, B, C:Single ): IntBool;
function VPF_logtoC( Y:cfVector; X:pfVector; size:UIntSize ): IntBool;
CUDA function C/C++#include <cudaVFmath.h>
int cudaVF_log( fVector d_Y, fVector d_X, ui size );
int cudaVFx_log( fVector d_Y, fVector d_X, ui size, float A, float B, float C );
int cusdVFx_log( fVector d_Y, fVector d_X, ui size, float *d_A, float *d_B, float *d_C );
int VFcu_log( fVector h_Y, fVector h_X, ui size );
int VFxcu_log( fVector h_Y, fVector h_X, ui size, float A, float B, float C );
CUDA function Pascal/Delphiuses VFmath;
function cudaVF_log( d_Y, d_X:fVector; size:UIntSize ): IntBool;
function cudaVFx_log( d_Y, d_X:fVector; size:UIntSize; A, B, C:Single ): IntBool;
function cusdVFx_log( d_Y, d_X:fVector; size:UIntSize; d_A, d_B, d_C:PSingle ): IntBool;
function VFcu_log( h_Y, h_X:fVector; size:UIntSize ): IntBool;
function VFxcu_log( h_Y, h_X:fVector; size:UIntSize; A, B, C:Single ): IntBool;
Descriptionsimple versions: Yi = ln( Xi )
expanded versions: Yi = C * ln( A*Xi+B )
The "logarithmus naturalis", i.e. the logarithm to the basis of Euler's constant e is calculated.
The logarithm of polar complex numbers is most naturally stored in cartesian format, as log{Mag@Arg} = {Mag,Arg}. Therefore, the VPF_ version exists only with the result in a cfVector.
Error handlingReal versions: DOMAIN errors occur in the case of negative Xi (including −0.0), with NAN ("not-a-number") as the default result. SING errors occur for Xi= +0.0 and yield a result of -HUGE_VAL. In the complex version, numbers with an imaginary part of zero are always treated as real numbers; therefore, an argument {0, 0} is treated as a real 0, causing a SING error with the default result {-HUGE_VAL, 0}.
Return valueFALSE (0), if no error occurred, otherwise TRUE (non-zero)
See alsoVF_exp,   VF_log2,   VF_log10,   VF_pow,   log

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