Sub

Performs element by element subtraction of one vector from another.

Syntax

IppStatus ippsSub_32f_A24 (const Ipp32f* pSrc1, const Ipp32f* pSrc2, Ipp32f* pDst, Ipp32s len);

IppStatus ippsSub_64f_A53 (const Ipp64f* pSrc1, const Ipp64f* pSrc2, Ipp64f* pDst, Ipp32s len);

IppStatus ippsSub_32fc_A24 (const Ipp32fc* pSrc1, const Ipp32fc* pSrc2, Ipp32fc* pDst, Ipp32s len);

IppStatus ippsSub_64fc_A53 (const Ipp64fc* pSrc1, const Ipp64fc* pSrc2, Ipp64fc* pDst, Ipp32s len);

Parameters

pSrc1	Pointer to the first source vector.
pSrc2	Pointer to the second source vector.
pDst	Pointer to the destination vector.
len	Number of elements in the vectors.

Description

The function ippsSub is declared in the ippvm.h file. This function performs element by element subtraction of the vector pSrc2 from the vector pSrc1, and stores the result in the corresponding element of the vector pDst.

For single precision data:

function flavors ippsSub_32f_A24 and ippsSub_32fc_A24 guarantee 24 correctly rounded bits of significand, including the implied bit, with the maximum guaranteed error within 1 ulp.

For double precision data:

function flavors ippsSub_64f_A53 and ippsSub_64fc_A53 guarantee 53 correctly rounded bits of significand, including the implied bit, with the maximum guaranteed error within 1 ulp.

The computation is performed as follows:

pDst[n] = (pSrc1[n]) - (pSrc2[n]), 0 ≤ n < len.

The example below shows how to use the function ippsSub.

Return Values

ippStsNoErr	Indicates no error.
ippStsNullPtrErr	Indicates an error when pSrc1, pSrc2 or pDst pointer is NULL.
ippStsSizeErr	Indicates an error when len is less than or equal to 0.

Using ippsSub Function

IppStatus ippsSub_32f_A24_sample(void)

const Ipp32f x1[4] = {+4.885, -0.543, -3.809, -4.953};

const Ipp32f x2[4] = {-0.543, -3.809, -4.953, +4.885};

Ipp32f  y[4];

	IppStatus st = ippsSub_32f_A24( x1, x2, y, 4 );

	printf(" ippsSub_32f_A24:\n");

	printf(" x1 = %+.3f %+.3f %+.3f %+.3f \n", x1[0], x1[1], x1[2], x1[3]);

	printf(" x2 = %+.3f %+.3f %+.3f %+.3f \n", x2[0], x2[1], x2[2], x2[3]);

	printf(" y  = %+.3f %+.3f %+.3f %+.3f \n",  y[0],  y[1],  y[2],  y[3]);

	return st;

Output results:

 ippsSub_32f_A24:

 x1 = +4.885 -0.543 -3.809 -4.953

 x2 = -0.543 -3.809 -4.953 +4.885

  y = +5.428 +3.266 +1.144 -9.838