question: @ Override public double [ ] analyse ( double [ ] frame ) { if ( frame . length != getFrameLengthSamples ( ) ) throw new IllegalArgumentException ( "Expected frame of length " + getFrameLengthSamples ( ) + ", got " + frame . length ) ; System . arraycopy ( frame , 0 , real , 0 , frame . length ) ; if ( real . length > frame . length ) Arrays . fill ( real , frame . length , real . length , 0 ) ; FFT . realTransform ( real , false ) ; return FFT . computePowerSpectrum_FD ( real ) ; }
target:  Apply this FrameBasedAnalyser to the given data.