added row and column functions

David Mayerich
1 parent ff4ee63d
Showing 1 changed file with 23 additions and 0 deletions Show diff stats
stim/math/matrix.h
@@ -245,6 +245,14 @@ public:
 		return a - b;
 	}
  
+	/// Sum all elements in the matrix
+	T sum() const {
+		size_t N = R * C;								//calculate the number of elements in the matrix
+		T s = (T)0;										//allocate a register to store the sum
+		for (size_t n = 0; n < N; n++) s += M[n];		//perform the summation
+		return s;
+	}
+
 	/// Sort rows of the matrix by the specified indices
 	matrix<T> sort_rows(size_t* idx) const {
 		matrix<T> result(C, R);					//create the output matrix
@@ -267,6 +275,21 @@ public:
 		return result;
 	}
  
+	/// Return the column specified by index i
+	matrix<T> col(size_t i) {
+		matrix<T> c(R, 1);										//create a single column matrix
+		memcpy(c.data(), &data()[R*i], C * sizeof(T));				//copy the column
+		return c;
+	}
+
+	/// Return the row specified by index i
+	matrix<T> row(size_t i) {
+		matrix<T> r(1, C);										//create a single row matrix
+		for (size_t c = 0; c < C; c++)
+			r(0, c) = at(i, c);
+		return r;
+	}
+
 	std::string toStr() const {
 		std::stringstream ss;