spectrumanalyser.cpp: In member function 'void SpectrumAnalyserThread::calculateSpectrum(const QByteArray&, int, int)': spectrumanalyser.cpp:138:59: error: 'sqrt' was not declared in this scope Change-Id: Ib43c693d73d2342059092094cfc3f48a0f73b4bc Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>