Created
January 28, 2013 13:18
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Simple matrix multiplication
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| #include <stdio.h> | |
| typedef struct { | |
| int nrows, ncols; | |
| float *data; | |
| } matrix_t; | |
| float constC(int i, int j, matrix_t A, matrix_t B) { | |
| int k; | |
| float res = 0.0; | |
| for (k = 0; k < A.nrows; k++) { | |
| res += A.data[i + (k*A.nrows)]*B.data[j*B.ncols + k]; | |
| } | |
| return res; | |
| } | |
| int main() { | |
| matrix_t A; | |
| A.nrows = 5; | |
| A.ncols = 5; | |
| A.data = (float *)malloc(A.ncols*A.nrows*sizeof(float)); | |
| int k; | |
| for (k = 0; k < A.ncols*A.nrows; k++) { | |
| A.data[k] = k % 9; | |
| } | |
| matrix_t B; | |
| B.nrows = 5; | |
| B.ncols = 5; | |
| B.data = (float *)malloc(B.ncols*B.nrows*sizeof(float)); | |
| for (k = 0; k < B.ncols*B.nrows; k++) { | |
| B.data[k] = k % 7; | |
| } | |
| matrix_t C; | |
| C.nrows = 5; | |
| C.ncols = 5; | |
| C.data = (float *)malloc(C.ncols*C.nrows*sizeof(float)); | |
| int i, j; | |
| if (A.nrows != B.ncols) { | |
| return -1; | |
| } | |
| for (i = 0; i < A.nrows; i++) { | |
| for(j = 0; j < B.ncols; j++) { | |
| C.data[i + j*C.ncols] = constC(i,j,A,B); | |
| printf("C_(%d,%d) = %f\n", i,j,C.data[i + j*C.ncols]); | |
| } | |
| } | |
| return 0; | |
| } |
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