How does your thread look like? Add in *.h file
Qt Code: 
  1. Q_SIGNALS:
  2. void currentEquitation(QString);
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In the cpp, where you calculate a new equation simple do
Qt Code: 
  1. Q_EMIT currentEquitation("Equitation foo");
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And then in your GUI class where you start your thread (assuming it is called thread and you have a QLabel called label):
Qt Code: 
  1. QObject::connect(thread, SIGNAL(currentEquitation(QString)), label, SLOT(setText(QString)));
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That's all.