Svenska ElektronikForumet

Kod: Markera allt

Create matrix
  1.000000 76.000000 86.000000  1.000000  5.000000
  1.000000  5.000000 -6.000000  0.000000  3.000000
 -5.000000  7.000000  3.000000 87.000000  3.000000
 -8.000000  3.000000  1.000000  4.000000 -1.000000
  7.000000  9.000000  1.000000 28.000000  4.000000

Cut a matrix
  1.000000  1.000000 -5.000000
  0.000000  0.000000  0.000000
  0.000000  0.000000  0.000000

Kod: Markera allt

matrix* cut(matrix* a, int start_n, int stop_n, int start_m, int stop_m) {

	int in_columns = a->column;
	float* data = a->data + start_n * in_columns + start_m;

	// Create the output
	matrix* out = initMatrix(stop_n - start_n + 1, stop_m - start_m + 1);
	float* ptr = out->data;
	int out_columns = out->column;

	// Instead of having two for loops, we just copy the whole row at once.
	for (int i = start_n; i < stop_n + 1; i++) {
		memcpy(ptr, data, sizeof(float) * out_columns);
		ptr += out_columns;
		data += in_columns;
	}

	return out;
}

Kod: Markera allt

matrix* svd_result = create(known_data, m, n);
matrix* svd_test = create(start_data, m, n);
// kör algoritmer
// ...
if(!matrix_equal(svd_test, svd_result))
  printf("svd test failed\n");
else
  printf("svd test passed\n");

Kod: Markera allt

matrix* triu(matrix* a, int shift){

	// Get info about matrix a
	int n = a->row;
	int m = a->column;
	float* ptr_a = a->data;

	matrix* out = initMatrix(n, m);
	float* ptr_out = out->data;

	// Create a triangular matrix
	for(int i = 0; i < n; i++){
		for(int j = 0; j < m; j++){
			// Do the "jump"
			if(j == 0){
				j = i + shift; // When we are at column 0 again, jump then n rows + shift at the right
			}
			// Write
			if(j != m)
				*((ptr_out + i*n) + j) = *((ptr_a + i*n) + j);
		}
	}

	return out;
}