WIdget relationship with Main Window

[Robobulls]

Hello all, I am fairly new to Qt so do not know all the ins and outs yet but I am attepting to create a simple matrix program with the results beign that when one parameter changes in the main window the widget is affected and shows the results. I have been reading online forums and all seem to say that interaction with Ui of the main window and the Ui of the widget is not allowed I also found another thread with a sample code on how to make it work (I will also post in bottom.) the code seemed to work but when attempting to compile several error messages came up

#include <QMainWindow>
#include "array.h"
#include "matrix.h"
//trying to get windows to recognize Matrix ui
namespace Ui {
  class MainWindow;
}
 
class MainWindow : public QMainWindow
{
  Q_OBJECT
 
public:
  explicit MainWindow(QWidget *parent = 0);
  ~MainWindow();
  Ui::MainWindow *ui;//made ui public instead of private
  Ui::Matrix*yw;//Here is the change I was recomended to add the widget class Ui to my main window
 
 
 
private:
 
 
protected:
  void mousePressEvent(QMouseEvent * e);
private slots:
  void on_radioButton_clicked(bool checked);
};
 
#endif // MAINWINDOW_H

#include <QMainWindow>
#include "array.h"
#include "matrix.h"
//trying to get windows to recognize Matrix ui
namespace Ui {
  class MainWindow;
}

class MainWindow : public QMainWindow
{
  Q_OBJECT
  
public:
  explicit MainWindow(QWidget *parent = 0);
  ~MainWindow();
  Ui::MainWindow *ui;//made ui public instead of private
  Ui::Matrix*yw;//Here is the change I was recomended to add the widget class Ui to my main window
  


private:


protected:
  void mousePressEvent(QMouseEvent * e);
private slots:
  void on_radioButton_clicked(bool checked);
};

#endif // MAINWINDOW_H

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Then in my Cpp file i added this line

void MainWindow::on_radioButton_clicked(bool checked)
{
  yw->label->setText("on");//Also recommendation
}

void MainWindow::on_radioButton_clicked(bool checked)
{
  yw->label->setText("on");//Also recommendation
}

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here is the error I recieved after compilation

ui_mainwindow.h:39: error: 'Matrix' does not name a type//

When this did'nt work I made some changes to the Cpp again attempting to establish a parent child relationship with the widget and main window but I am not sure if I was succesful

ui(new Ui::MainWindow),matrix(new Ui::Matrix)//here is what I changed
{
  ui->setupUi(this);
  matrix->setupUi(this->ui->centralWidget);//Added this

ui(new Ui::MainWindow),matrix(new Ui::Matrix)//here is what I changed
{
  ui->setupUi(this);
  matrix->setupUi(this->ui->centralWidget);//Added this

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I am at a bit of a dead end with how to approach this now hope someone can help