computes a matrix-vector product on a single processor.

/* serial_mat_vect.c -- computes a matrix-vector product on a single processor.
*
* Input:
* m, n: order of matrix
* A, x: the matrix and the vector to be multiplied
*
* Output:
* y: the product vector
*
* Note: A, x, and y are statically allocated.
*
* See Chap 5, p. 78 & ff in PPMPI.
*/
#include

#define MAX_ORDER 100

typedef float MATRIX_T[MAX_ORDER][MAX_ORDER];

main() {
MATRIX_T A;
float x[MAX_ORDER];
float y[MAX_ORDER];
int m, n;

void Read_matrix(char* prompt, MATRIX_T A, int m, int n);
void Read_vector(char* prompt, float v[], int n);
void Serial_matrix_vector_prod(MATRIX_T A, int m, int n,
float x[], float y[]);
void Print_vector(float y[], int n);

printf("Enter the order of the matrix (m x n)\n");
scanf("%d %d", &m, &n);
Read_matrix("the matrix", A, m, n);
Read_vector("the vector", x, m);
Serial_matrix_vector_prod(A, m, n, x, y);
Print_vector(y, n);
} /* main */


/*****************************************************************/
void Read_matrix(
char* prompt /* in */,
MATRIX_T A /* out */,
int m /* in */,
int n /* in */) {
int i, j;

printf("Enter %s\n", prompt);
for (i = 0; i < m; i++)
for (j = 0; j < n; j++)
scanf("%f", &A[i][j]);
} /* Read_matrix */


/*****************************************************************/
void Read_vector(
char* prompt /* in */,
float v[] /* out */,
int n /* in */) {
int i;

printf("Enter %s\n", prompt);
for (i = 0; i < n; i++)
scanf("%f", &v[i]);
} /* Read_vector */


/*****************************************************************/
void Serial_matrix_vector_prod(
MATRIX_T A /* in */,
int m /* in */,
int n /* in */,
float x[] /* in */,
float y[] /* out */) {

int k, j;

for (k = 0; k < m; k++) {
y[k] = 0.0;
for (j = 0; j < n; j++)
y[k] = y[k] + A[k][j]*x[j];
}
} /* Serial_matrix_vector_prod */


/*****************************************************************/
void Print_vector(
float y[] /* in */,
int n /* in */) {
int i;

printf("Result is \n");
for (i = 0; i < n; i++)
printf("%4.1f ", y[i]);
printf("\n");
} /* Print_vector */