X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Flinal%2Fmatrix.h;h=1c831be6b11cf6f4181366017c739c9ba5e4fd30;hb=2826730b5d68d1ad74dc6363af43ca796f96caa2;hp=f18eb2f4cfb52504214b84015688e46d0d7be121;hpb=77edbd42b918f3448ab4004dfe96b8a96621c348;p=libs%2Fmath.git

diff --git a/source/linal/matrix.h b/source/linal/matrix.h
index f18eb2f..1c831be 100644
--- a/source/linal/matrix.h
+++ b/source/linal/matrix.h
@@ -13,6 +13,9 @@ A general mathematical matrix with M rows and N columns.
 template<typename T, unsigned M, unsigned N>
 class Matrix
 {
+public:
+	typedef T ElementType;
+
 private:
 	T data[M*N];
 
@@ -25,11 +28,20 @@ public:
 	static Matrix from_columns(const Vector<T, M> *);
 	static Matrix from_rows(const Vector<T, N> *);
 
+	unsigned rows() const { return M; }
+	unsigned columns() const { return N; }
+
 	T &element(unsigned i, unsigned j) { return data[i+M*j]; }
 	const T &element(unsigned i, unsigned j) const { return data[i+M*j]; }
 	T &operator()(unsigned i, unsigned j) { return element(i, j); }
 	const T &operator()(unsigned i, unsigned j) const { return element(i, j); }
 
+	template<unsigned P, unsigned Q>
+	Matrix<T, P, Q> select(const Vector<unsigned, P> &, const Vector<unsigned, Q> &) const;
+
+	template<unsigned P, unsigned Q>
+	Matrix<T, P, Q> block(unsigned, unsigned) const;
+
 	Matrix &operator*=(T);
 	Matrix &operator/=(T);
 	Matrix &operator+=(const Matrix &);
@@ -81,6 +93,28 @@ inline Matrix<T, M, N> Matrix<T, M, N>::from_rows(const Vector<T, N> *v)
 	return m;
 }
 
+template<typename T, unsigned M, unsigned N>
+template<unsigned P, unsigned Q>
+inline Matrix<T, P, Q> Matrix<T, M, N>::select(const Vector<unsigned, P> &row_indices, const Vector<unsigned, Q> &col_indices) const
+{
+	Matrix<T, P, Q> r;
+	for(unsigned j=0; j<P; ++j)
+		for(unsigned i=0; i<Q; ++i)
+			r(j, i) = element(row_indices[j], col_indices[i]);
+	return r;
+}
+
+template<typename T, unsigned M, unsigned N>
+template<unsigned P, unsigned Q>
+inline Matrix<T, P, Q> Matrix<T, M, N>::block(unsigned y, unsigned x) const
+{
+	Matrix<T, P, Q> r;
+	for(unsigned j=0; j<P; ++j)
+		for(unsigned i=0; i<Q; ++i)
+			r(j, i) = element(y+j, x+i);
+	return r;
+}
+
 template<typename T, unsigned M, unsigned N>
 inline Matrix<T, M, N> &Matrix<T, M, N>::operator*=(T s)
 {