An array matrix problem in a class

Asuralm · 12-06-2007, 07:11 AM

Hi all:

Say I have an matrix type defined as

Code:

typedef NRMatrix<float> Mat_SP

To define a matrix type the most obvious way is to declare like

Code:

Mat_SP mymat(300,300);

Now if I want this:

Code:

class myclass{
private:
    Mat_SP mymat;
public:
    inline myclass(){ mymat = Mat_SP(300, 300);}
}

Why this always gave me the error in runtime saying the "segmentation fault" please?

Is there a way of declaring the size of my matrix when constructing the object please?

Thanks in advance.

indienick · 12-06-2007, 07:56 AM

I'm not too knowledgable with C++ (as I'm assuming this is), but if you're trying to instantiate an object, shouldn't you drop in the "new" keyword somewhere?

Code:

Mat_SP mymat = new Mat_SP(300,300);

Asuralm · 12-06-2007, 07:59 AM

No, it doesn't compile that way but I don't know why C++ doesn't work that way.
Here is the class of the NRMat:

Code:

template<class T>
class NRMat{
private:
    int nn;
    int mm;
    T **v;
public:
    NRMat();
    NRMat(int n, int m); // zero_based array
    NRMat(const T &a, int n, int m); // initialize to constant
    NRMat(const T *a, int n, int m);// initialize to array
    NRMat(const NRMat &rhs);//copy constructor
    NRMat & operator=(const NRMat &rhs);
    NRMat & operator=(const T &a);
    inline T* operator[](const int i);
    inline const T* operator[](const int i) const;
    inline int nrows() const;
    inline int ncols() const;
    ~NRMat();
};

indienick · 12-06-2007, 08:57 AM

Okay - so, all of the public functions and constructors I see here are just being prototyped, like I would see in a header (.h) file. This may seem like a dumb question, but are you "#include"ing the file with the completely defined functions and constructors, or are you hand-writing them in yourself?

Asuralm · 12-06-2007, 09:09 AM

yeah, sure I included everything properly. Actually what I really want to do is to declare a matrix field in the class definition. Then, I can define the size of the matrix when constructe the object. Obviously the matrix size can't be declared explicitly in class definition. But how to define the size of the matrix in construction ???