Ln

Computes the natural logarithm of each element of a vector.

Syntax

IppStatus ippsLn_32f(const Ipp32f* pSrc, Ipp32f* pDst, int len);

IppStatus ippsLn_64f(const Ipp64f* pSrc, Ipp64f* pDst, int len);

IppStatus ippsLn_64f32f(const Ipp64f* pSrc, Ipp32f* pDst, int len);

IppStatus ippsLn_32f_I(Ipp32f* pSrcDst, int len);

IppStatus ippsLn_64f_I(Ipp64f* pSrcDst, int len);

IppStatus ippsLn_16s_Sfs(const Ipp16s* pSrc, Ipp16s* pDst, int len, int scaleFactor);

IppStatus ippsLn_32s_Sfs(const Ipp32s* pSrc, Ipp32s* pDst, int len, int scaleFactor);

IppStatus ippsLn_32s16s_Sfs(const Ipp32s* pSrc, Ipp16s* pDst, int len, int scaleFactor);

IppStatus ippsLn_16s_ISfs(Ipp16s* pSrcDst, int len, int scaleFactor);

IppStatus ippsLn_32s_ISfs(Ipp32s* pSrcDst, int len, int scaleFactor);

Parameters

pSrc	Pointer to the source vector.
pDst	Pointer to the destination vector.
pSrcDst	Pointer to the source and destination vector for the in-place operation.
len	Number of elements in the vector
scaleFactor	Scale factor, refer to Integer Scaling.

Description

The function ippsLn is declared in the ipps.h file. This function computes the natural logarithm of each element of the vector pSrc and stores the result in pDst as given by

pDst[n] = log_e (pSrc[n])

The in-place flavors of ippsLn compute the natural logarithm of each element of the vector pSrcDst and store the result in pSrcDst as given by

pSrcDst[n] = log_e (pSrcDst[n])

If the function ippsLn encounters a zero or negative value in the input, it returns a warning status and continues execution with the corresponding result value (see appendix A "Handling of Special Cases" for more information).

The example below shows how to call the function ippsLn_32f_I.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when the pSrc, pDst, or pSrcDst pointer is NULL.
ippStsSizeErr	Indicates an error when len is less than or equal to 0.
ippStsLnZeroArg	Indicates a warning for zero-valued input vector elements.
ippStsLnNegArg	Indicates a warning for negative input vector elements.

Using the ippsLn Function

IppStatus ln32f(void) {

      Ipp32f x[4] = {-1, (float)IPP_E, 0, (float)(exp(1.234567))};

      IppStatus st = ippsLn_32f_I(x, 4);

      printf_32f(“Ln =”, x, 4, st);

      return st;

Output:

    -- warning 8, Negative value(s) of argument in the Ln function

    Ln = -1.#IND00 1.000000 -1.#INF00 1.234567