householder-example.h

/// Example code for in-place multiplcation by a Householder matrix
void inPlaceHouseholder(double *arr, int size) {
	// Division is slower, so compute this statically if you can
	const double factor = -2.0/size;

	double sum = 0;
	for (int i = 0; i < size; ++i) {
		sum += arr[i];
	}

	sum *= factor;
	
	for (int i = 0; i < size; ++i) {
		arr[i] += sum;
	}
};