Add basic description for all classes

[libs/math.git] / source / linal / squarematrix.h

diff --git a/source/linal/squarematrix.h b/source/linal/squarematrix.h
index 6cda86a5baa6b202ec00dba93acb0a152b03a985..0af9a7454852cb5106382fcda2a4f1c5e2aaf824 100644 (file)
--- a/source/linal/squarematrix.h
+++ b/source/linal/squarematrix.h
@@ -1,26 +1,100 @@
 #ifndef MSP_LINAL_SQUAREMATRIX_H_
 #define MSP_LINAL_SQUAREMATRIX_H_
 
+#include <stdexcept>
 #include "matrix.h"
 
 namespace Msp {
 namespace LinAl {
 
+class not_invertible: public std::domain_error
+{
+public:
+       not_invertible(): domain_error(std::string()) { }
+       virtual ~not_invertible() throw() { }
+};
+
+/**
+A mathematical matrix with S rows and columns.  Some operations are provided
+here that are only possible for square matrices.
+*/
 template<typename T, unsigned S>
 class SquareMatrix: public Matrix<T, S, S>
 {
 public:
-       SquareMatrix();
-       SquareMatrix(const T *);
+       SquareMatrix() { }
+       SquareMatrix(const T *d): Matrix<T, S, S>(d) { }
        template<typename U>
-       SquareMatrix(const Matrix<U, S, S> &);
+       SquareMatrix(const Matrix<U, S, S> &m): Matrix<T, S, S>(m) { }
+
        static SquareMatrix identity();
 
        SquareMatrix &operator*=(const SquareMatrix &);
 
-       void invert();
+       SquareMatrix &invert();
 };
 
+template<typename T, unsigned S>
+inline SquareMatrix<T, S> SquareMatrix<T, S>::identity()
+{
+       SquareMatrix<T, S> m;
+       for(unsigned i=0; i<S; ++i)
+               m(i, i) = T(1);
+       return m;
+}
+
+template<typename T, unsigned S>
+SquareMatrix<T, S> &SquareMatrix<T, S>::operator*=(const SquareMatrix<T, S> &m)
+{
+       return *this = *this*m;
+}
+
+template<typename T, unsigned S>
+SquareMatrix<T, S> &SquareMatrix<T, S>::invert()
+{
+       SquareMatrix<T, S> r = identity();
+       for(unsigned i=0; i<S; ++i)
+       {
+               if(this->element(i, i)==T(0))
+               {
+                       unsigned pivot = i;
+                       for(unsigned j=i+1; j<S; ++j)
+                               if(abs(this->element(j, i))>abs(this->element(pivot, i)))
+                                       pivot = j;
+
+                       if(pivot==i)
+                               throw not_invertible();
+
+                       this->exchange_rows(i, pivot);
+                       r.exchange_rows(i, pivot);
+               }
+
+               for(unsigned j=i+1; j<S; ++j)
+               {
+                       T a = -this->element(j, i)/this->element(i, i);
+                       this->add_row(i, j, a);
+                       r.add_row(i, j, a);
+               }
+
+               T a = T(1)/this->element(i, i);
+               this->multiply_row(i, a);
+               r.multiply_row(i, a);
+       }
+
+       for(unsigned i=S; i-->0; )
+               for(unsigned j=i; j-->0; )
+                       r.add_row(i, j, -this->element(j, i));
+
+       return *this = r;
+}
+
+template<typename T, unsigned S>
+inline SquareMatrix<T, S> invert(const SquareMatrix<T, S> &m)
+{
+       SquareMatrix<T, S> r = m;
+       return r.invert();
+}
+
 } // namespace LinAl
 } // namespace Msp