Trace

Computes matrix trace.

Syntax

Case 1: Matrix operation

IppStatus ippmTrace_m_32f(const Ipp32f* pSrc, int srcStride1, int srcStride2, int widthHeight, Ipp32f* pDst);

IppStatus ippmTrace_m_64f(const Ipp64f* pSrc, int srcStride1, int srcStride2, int widthHeight, Ipp64f* pDst);

IppStatus ippmTrace_m_32f_P(const Ipp32f** ppSrc, int srcRoiShift, int widthHeight, Ipp32f* pDst);

IppStatus ippmTrace_m_64f_P(const Ipp64f** ppSrc, int srcRoiShift, int widthHeight, Ipp64f* pDst);

Case 2: Matrix array operation

IppStatus ippmTrace_ma_32f(const Ipp32f* pSrc, int srcStride0, int srcStride1, int srcStride2, int widthHeight, Ipp32f* pDst, int count);

IppStatus ippmTrace_ma_64f(const Ipp64f* pSrc, int srcStride0, int srcStride1, int srcStride2, int widthHeight, Ipp64f* pDst, int count);

IppStatus ippmTrace_ma_32f_P(const Ipp32f** ppSrc, int srcRoiShift, int srcStride0, int widthHeight, Ipp32f* pDst, int count);

IppStatus ippmTrace_ma_64f_P(const Ipp64f** ppSrc, int srcRoiShift, int srcStride0, int widthHeight, Ipp64f* pDst, int count);

IppStatus ippmTrace_ma_32f_L(const Ipp32f** ppSrc, int srcRoiShift, int srcStride1, int srcStride2, int widthHeight, Ipp32f* pDst, int count);

IppStatus ippmTrace_ma_64f_L(const Ipp64f** ppSrc, int srcRoiShift, int srcStride1, int srcStride2, int widthHeight, Ipp64f* pDst, int count);

Parameters

pSrc, ppSrc	Pointer to the source matrix or array of matrices.
srcStride0	Stride between the matrices in the source array.
srcStride1	Stride between the rows in the source matrix(ces).
srcStride2	Stride between the elements in the source matrix(ces).
srcRoiShift	ROI shift in the source matrix(ces).
pDst	Pointer to the destination value or array of values.
widthHeight	Size of the square matrix.
count	Number of matrices in the array.

Description

The function ippmTrace is declared in the ippm.h header file. The function sums up the elements along the principal diagonal of the source matrix and stores the result in pDst. The following formula illustrates how trace is calculated:

If the operation is performed on a vector array, the resulting values are stored sequentially in the array with the pointer pDst.

The following example demonstrates how to use the function ippmTrace_ma_32f_P. For more information, see also examples in Getting Started.

ippmTrace_ma_32f_P

IppStatus trace_ma_32f_P(void) {
   /*
    // Source data:
    // 2 matrices with widthHeight=3 
    */

    Ipp32f src[6*6] = { 1, 0, 0, 1, 0, 1,
                        0, 1, 1, 0, 0, 1,
                        0, 0, 1, 1, 0, 1,
                        2, 0, 0, 2, 0, 2,
                        0, 2, 2, 0, 0, 2,
                        0, 0, 2, 2, 0, 2};
    /*
    // Nonzero elements of interest are referred by mask using 
    // pointer descriptor 
    */
    int widthHeight=3;
    int count=2;
    int srcRoiShift= 0;
    int srcStride0 = 3*6*sizeof(Ipp32f);

    Ipp32f* ppSrc[3*3] = { src,    src+3,  src+5,
                           src+7,  src+8,  src+11,
                           src+14, src+15, src+17 };

    Ipp32f pDst[2]; /* Destination is array of values */

    IppStatus status = ippmTrace_ma_32f_P((const Ipp32f**)ppSrc,
        srcRoiShift, srcStride0, widthHeight, pDst, 2);

    /*

    // It is recommended to check return status

    // to detect wrong input parameters, if any

*/

    if (status == ippStsNoErr) {

        printf_va_Ipp32f("Dst is 2 values:", pDst, 2, 1, status);

    } else {

        printf("Function returns status: %s \n", ippGetStatusString(status));

    return status;
}

The program above produces the following output:

Dst is 2 values:

3.000000 6.000000

Return Values

ippStsOk	Returns no error.
ippStsNullPtrErr	Returns an error when at least one input pointer is NULL.
ippStsSizeErr	Returns an error when the input size parameter is equal to 0.
ippStsStrideMatrixErr	Returns an error when the stride value is not positive or not divisible by the size of the data type.
ippStsRoiShiftMatrixErr	Returns an error when a `roiShift` value is negative or not divisible by the size of the data type.
ippStsCountMatrixErr	Returns an error when a count value is less or equal to zero.