undefined reference to ..issue involving the QVector class

Hi All,
I am a newbie and I need help with this (urgently if possible).
I am deriving a template class from QVector in order to add more functionality to be able to convert the types store in the QVector and also carry out math operations like multiplications.

Code:

#ifndef MVECTOR_H
#define MVECTOR_H
#include <QVector>
#include <typeinfo>
#include <QString>
 
template <typename T>
class mVector:public QVector<T>
{
 
    bool numeric;
public:
    mVector<T>():QVector<T>(){numeric=false;} //the vector contains non-numeric by default.
    mVector<T> operator*(mVector<T> a);
    bool isNumeric();
    mVector<float> toNumeric();
    mVector<QString> toString();
    mVector<T> operator=(mVector<T>);
};
#endif //
 
 
#include "mvector.h"
 
template <typename T>
mVector<T> mVector<T>::operator*(mVector<T> a){
    mVector<T> c;
    if(this->size()==a.size())
    {
       for(int i=0;i<a.size();i++)
           c[i]=this->at(i)*a[i];
    }
    return c;
}
template <typename T>
bool mVector<T>::isNumeric(){
    return numeric;
}
 
template <typename T>
mVector<float> mVector<T>::toNumeric(){
    mVector<float> tm;
    if(!numeric){
        for(int i=0;i<this->size();i++)
            tm.append(float(this->at(i)));
        //this=&tm;
    }
    tm.numeric=true;
    return tm;
}
 
template <typename T>
mVector<QString> mVector<T>::toString(){
    mVector<QString> strv;
    if(numeric){
        for(int i=0;i<this->size();i++)
        {
            strv.append(QString::number(this->at(i)));
        }
    }
    strv.numeric=false;
    return strv;
}
template <typename T>
mVector<T> mVector<T>::operator=(mVector<T> a){
    this->resize(a.size());
    for(int i=0;i<this->size();i++)
        *this[i]=a[i];
    return *this;
}

creating an instance and calling any of its functions

Code:

mVector<QString> s;
    mVector<float> n;
    s.append("3.445");
    n=s.toNumeric();

gives this error. i included all dependencies to no avail.

./debug\mainwindow.o:L:\Qt Codes\LoadCombination\LoadCombination-build-desktop/../LoadCombination/mainwindow.cpp:156: undefined reference to `mVector<float>::operator=(mVector<float>)'

Thanks in advance for your intervention and help.