Pow43Scale

Raises a vector to the power of 4/3 with scaling.

Syntax

IppStatus ippsPow43Scale_16s32s_Sf(const Ipp16s* pSrc, Ipp32f* pDst, const Ipp16s *pScaleFactor, const Ipp32s *pBandOffset, int offset, int bandsNumber, int groupLen, int scalef);

Parameters

pSrc	Pointer to the input data vector.
pDst	Pointer to the output data vector.
pScaleFactor	Pointer to the data array containing scale factors. The size of the array must be not less than bandsNumber.
pBandOffset	Pointer to the vector of band offsets. The size of array must be not less than bandsNumber + 1.
offset	Scale factors offset.
bandsNumber	Number of bands to which scale factors are applied.
groupLen	Number of windows in the current group.
scalef	Scale factor of the output data.

Description

This function is declared in the ippac.h header file. The ippsPow43Scale function performs the following operation:

pDst[i] = pSrc[i]^4/3 * 2^{1/4(pScaleFactor[band] - offset)}.

This function does not perform any saturation so the user must consider overflow possibility. Absolute values of pSrc[i] must be less than 2¹⁴.

Below see an example of using ippsPow43Scale function.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when one of the specified pointers is NULL.
ippStsSizeErr	Indicates an error when groupLen or bandsNumber is less than 0.

ippsPow43Scale Usage

#undef SF_OFFSET

#define SF_OFFSET 100

IppStatus pow43scale(void)

  Ipp16s pSrc[40];

  Ipp32s pDst0[40], pDst1[40];

  Ipp16s pScaleFactor[5] = {65, 128, 163, 58, 100};

  Ipp32s pBandOffset0[6] = {0,1,3,8,13,20};

  Ipp32s pBandOffset1[6];

  int groupLen = 2;

  int bandsNumber = 5;

  int i;

  IppStatus st;

  for (i = 0; i < 40; i++)

    pSrc[i] = (Ipp16s)(100 * i);

  /* The are two ways of using ippsPow43Scale_16s32s_Sf when groupLen */

  /* is not equal to 1                                                */

  /* First way is to use function as is                               */

  st = ippsPow43Scale_16s32s_Sf(pSrc, pDst0, pScaleFactor, pBandOffset0,

                                SF_OFFSET, bandsNumber, groupLen, 0);

  if (st != ippStsOk) return st;

  /* The second way is to recalculate pBandOffset */

  pBandOffset1[0] = pBandOffset0[0];

  for (i = 0; i < bandsNumber; i++)

    pBandOffset1[i+1] = pBandOffset1[i] +

         (pBandOffset0[i+1] - pBandOffset0[i]) * groupLen;

  /* and use function ippsPow43Scale_16s32s_Sf with groupLen is equal to 1 */

  /* The result will be the same                                           */

  st = ippsPow43Scale_16s32s_Sf(pSrc, pDst1, pScaleFactor, pBandOffset1,

                               SF_OFFSET, bandsNumber, 1, 0);

  printf("\n pDst0 = ");

  for (i = 0; i < 40; i++)

    printf("%i ", pDst0[i]);

  printf("\n");

  printf("\n pDst1 = ");

  for (i = 0; i < 40; i++)

    printf("%i ", pDst1[i]);

  printf("\n");

  return st;

//Output:

//   pDst1 = 0 1 149709 257062 377244 507968 278884317

//           342520430 409269211 478864278 551089873

//           625767026 702744444 781892234 863097398

//           946260634 12 14 15 16 17 18 19 20 22 23

//           35751 37596 39464 41355 43267 45201 47155

//           49130 51125 53140 55174 57227 59298 61388

//

//   pDst1 = 0 1 149709 257062 377244 507968 278884317

//           342520430 409269211 478864278 551089873

//           625767026 702744444 781892234 863097398

//           946260634 12 14 15 16 17 18 19 20 22 23

//           35751 37596 39464 41355 43267 45201 47155

//           49130 51125 53140 55174 57227 59298 61388