Basics of MATLAB and Beyond

clfpolar(t,gdb)In this case you must use a modified version of polar that interpretsa zero radius as a 0 dB value which should go at the outer limit of theplot. Negative decibel values should appear at smaller radii. I haveimplemented these ideas in the m-file negpolar (see companion software):negpolar(t,gdb)The negpolar function also omits the solid outer circle which, like thebox drawn around matlab’s default plot output, unnecessarily framesthe plot and can obscure the data that you are trying to display. A faintdotted grid is enough to put the plotted points in context. I will saymore about this in the section on Handle Graphics later (see page 65).17 Fourier TransformA theorem of mathematics says, roughly, that any function can be representedas a sum of sinusoids of different amplitudes and frequencies. TheFourier transform is the mathematical technique of finding the amplitudesand frequencies of those sinusoids. The Discrete Fourier Transform(DFT) is an algorithm that calculates the Fourier transform for numericaldata. The Fast Fourier Transform is an efficient implementation ofthe DFT. The following functions are available in matlab to do Fouriertransforms and related operations:c○ 2000 by CRC Press LLC