vsip_dmvprod_p - Matrix-Vector Product

Core

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While our Core implementation implements all functions given in the standard we are still working on completing this documentation.

Please refer to the VSIPL standard for a complete function reference of the Core profile until we have completed work on this documentation.

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6.1.9 vsip_dmvprod_p - Matrix-Vector Product

void vsip_mvprod_f(const vsip_mview_f *a, const vsip_vview_f *b, const vsip_vview_f *r); 
void vsip_cmvprod_f(const vsip_cmview_f *a, const vsip_cvview_f *b, const vsip_cvview_f *r);

Description

This function computes the product of a matrix and a vector, storing the result in an output vector. The operation performed is:

r =∑︁n a ·b i j=1 i,j j

for $i= 1,2,...,m$ , where $a$ is an $m ×n$ matrix, $b$ is a vector of length $n$ , and $r$ is the resulting vector of length $m$ .

This operation is equivalent to the matrix-vector product $r= a·b$ .

Parameters

const vsip_dmview_p* a: Input matrix of size $m × n$ .
const vsip_dvview_p* b: Input vector of length $n$ .
const vsip_dvview_p* r: Output vector of length $m$ that will store the result.

Example

vsip_mview_f *A; 
vsip_vview_f *b, *r; 
vsip_length m = 4, n = 3; 
 
// Create matrix and vectors 
A = vsip_mcreate_f(m, n, VSIP_ROW, VSIP_MEM_NONE); 
b = vsip_vcreate_f(n, VSIP_MEM_NONE); 
r = vsip_vcreate_f(m, VSIP_MEM_NONE); 
 
// Initialize matrix A and vector b with some values 
// Initialize A (4x3 matrix) 
for (vsip_index i = 0; i < m; i++) { 
    for (vsip_index j = 0; j < n; j++) { 
        vsip_mput_f(A, i, j, (float)(i*n + j + 1)); 
    } 
} 
 
// Initialize vector b 
vsip_vramp_f(1.0f, 1.0f, b);  // b = [1, 2, 3] 
 
// Compute matrix-vector product: r = A * b 
vsip_mvprod_f(A, b, r); 
 
// Print the result 
printf("Matrix A (%lux%lu):\n", m, n); 
for (vsip_index i = 0; i < m; i++) { 
    for (vsip_index j = 0; j < n; j++) { 
        printf("%8.2f ", vsip_mget_f(A, i, j)); 
    } 
    printf("\n"); 
} 
 
printf("\nVector b (%lu):\n", n); 
for (vsip_index i = 0; i < n; i++) { 
    printf("%8.2f ", vsip_vget_f(b, i)); 
} 
printf("\n"); 
 
printf("\nResult vector r (%lu):\n", m); 
for (vsip_index i = 0; i < m; i++) { 
    printf("%8.2f ", vsip_vget_f(r, i)); 
} 
printf("\n"); 
 
// Clean up 
vsip_malldestroy_f(A); 
vsip_valldestroy_f(b); 
vsip_valldestroy_f(r);

Notes

The input matrix $a$ must have dimensions $m × n$ .
The input vector $b$ must have length $n$ .
The output vector $r$ must have length $m$ .
This operation is equivalent to the matrix-vector product $r= a·b$ .
If you need to compute $T b ·a$ (vector-matrix product), use vsip_dvmprod_p instead.

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