kml_sparse_?csrsymv

Compute the product of a vector and a sparse matrix that is stored in the CSR format. The operation is defined as follows:

y = A * x

x and y are vectors, and A is a symmetric upper or lower triangle matrix stored in the CSR format (3-array variation) with one-based indexing.

Interface Definition

C interface:

kml_sparse_status_t kml_sparse_scsrsymv(const kml_sparse_fill_mode_t uplo, const KML_INT m, const float *a, const KML_INT *ia, const KML_INT *ja, const float *x, float *y);

kml_sparse_status_t kml_sparse_dcsrsymv(const kml_sparse_fill_mode_t uplo, const KML_INT m, const double *a, const KML_INT *ia, const KML_INT *ja, const double *x, double *y);

kml_sparse_status_t kml_sparse_ccsrsymv(const kml_sparse_fill_mode_t uplo, const KML_INT m, const KML_Complex8 *a, const KML_INT *ia, const KML_INT *ja, const KML_Complex8 *x, KML_Complex8 *y);

kml_sparse_status_t kml_sparse_zcsrsymv(const kml_sparse_fill_mode_t uplo, const KML_INT m, const KML_Complex16 *a, const KML_INT *ia, const KML_INT *ja, const KML_Complex16 *x, KML_Complex16 *y);

Fortran interface:

RES = KML_SPARSE_SCSRSYMV(UPLO, M, A, IA, JA, X, Y);

RES = KML_SPARSE_DCSRSYMV(UPLO, M, A, IA, JA, X, Y);

RES = KML_SPARSE_CCSRSYMV(UPLO, M, A, IA, JA, X, Y);

RES = KML_SPARSE_ZCSRSYMV(UPLO, M, A, IA, JA, X, Y);

Parameters

Parameter	Type	Description	Input/Output
uplo	Enumeration type kml_sparse_fill_mode_t uplo	Indicates whether the upper triangle or lower triangle of matrix A is used. U: upper triangle L: lower triangle	Input
m	Integer	Number of rows and columns in matrix A. The value range is [1, MAX_KML_INT].	Input
a	For scsrsymv, val is a single-precision floating-point array. For dcsrsymv, val is a double-precision floating-point array. For ccsrsymv, val is a single-precision complex number array. For zcsrsymv, val is a double-precision complex number array.	Non-zero elements in matrix A	Input
ia	Integer	Vector whose length is m+1. ia[i]-1 indicates the index of the first non-zero element in the ith row of matrix A in the val array.	Input
ja	Integer	ja[i] indicates the column number of the ith element of the val array in matrix A.	Input
x	For scsrsymv, x is a single-precision floating-point array. For dcsrsymv, x is a double-precision floating-point array. For ccsrsymv, x is a single-precision complex number array. For zcsrsymv, x is a double-precision complex number array.	Vector x	Input
y	For scsrsymv, y is a single-precision floating-point array. For dcsrsymv, y is a double-precision floating-point array. For ccsrsymv, y is a single-precision complex number array. For zcsrsymv, y is a double-precision complex number array.	Vector y, which is output after being updated.	Input/Output

The function does not verify the integrity of parameters. Ensure that the elements in ia and ja do not exceed the maximum index value of the input matrix.

Return Value

Function execution status. The enumeration type is kml_sparse_status_t.

Dependencies

C: "kspblas.h"

Fortran: "kspblas.f03"

Examples

C interface:

    kml_sparse_fill_mode_t uplo = KML_SPARSE_FILL_MODE_LOWER; 
    KML_INT m = 4; 
    float a[9] = {2, -3, 7, 1, -6, 8, -4, 5, 9}; 
    KML_INT ja[9] = {1, 2, 4, 3, 4, 1, 3, 4, 1}; 
    KML_INT ia[5] = {1, 4, 6, 9, 10}; 
    float x[4] = {1, 3, -2, 5}; 
    float y[4] = {-1, 1, 5, 3}; 
    kml_sparse_status_t status = kml_sparse_scsrsymv(uplo, m, a, ia, ja, x, y); 
 
    /* 
     *  Output Y: 
     *     31.000000     0.000000    16.000000     9.000000 
     * 
     */

Fortran interface:

    INTEGER(C_INT) :: UPLO = KML_SPARSE_FILL_MODE_LOWER 
    INTEGER(C_INT) :: M = 4 
    REAL(C_FLOAT) :: A(9), X(4), Y(4) 
    INTEGER(C_INT) :: JA(9), IA(5) 
    INTEGER(C_INT) :: STATUS  
    DATA A/2, -3, 7, 1, -6, 8, -4, 5, 9/ 
    DATA JA/1, 2, 4, 3, 4, 1, 3, 4, 1/ 
    DATA IA/1, 4, 6, 9, 10/ 
    DATA X/1, 3, -2, 5/ 
    DATA Y/-1, 1, 5, 3/  
    STATUS = KML_SPARSE_SCSRSYMV(UPLO, M, A, IA, JA, X, Y) 
    ! 
    !  OUTPUT Y: 
    !     31.000000     0.000000    16.000000     9.000000 
    ! 
    !

Parent topic: Sparse BLAS Level 2 and Level 3 Functions