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spec2dt

PURPOSE

Computes sampling interval from Nyquist frequency in spectrum

dT = spec2dt(S);

DESCRIPTION

```  SPEC2DT  Computes sampling interval from Nyquist frequency in spectrum

CALL : dT = spec2dt(S)

dT = sampling interval, unit: [m] if wave number spectrum, [s] else
S  = spectrum struct

Let wm be maximum frequency/wave number in spectrum,
then dT=pi/wm if angular frequency, dT=1/(2*wm) if natural frequency (Hz)```

CROSS-REFERENCE INFORMATION

This function calls:
 freqtype returns the frequency type of a Spectral density struct. getfield Get structure field contents. strcmp Compare strings.
This function is called by:
 Chapter2 % CHAPTER2 Modelling random loads and stochastic waves

SOURCE CODE

```01 function dT = spec2dt(S);
02 % SPEC2DT  Computes sampling interval from Nyquist frequency in spectrum
03 %
04 %  CALL : dT = spec2dt(S)
05 %
06 %         dT = sampling interval, unit: [m] if wave number spectrum, [s] else
07 %         S  = spectrum struct
08 %
09 %  Let wm be maximum frequency/wave number in spectrum,
10 %  then dT=pi/wm if angular frequency, dT=1/(2*wm) if natural frequency (Hz)
11
12 % Tested on Matlab 5.3
13 % Revised by es 25.05.00: help text + call to freqtype
14
15 ftype=freqtype(S);
16
17 n=length(getfield(S,ftype));
18
19 if strcmp(ftype,'w')
20   dT=pi/(S.w(n));
21 elseif strcmp(ftype,'f')
22   dT=1/(2*S.f(n)); % sampling interval=1/Fs
23 else
24     dT=pi/(S.k(n));
25 end
26
27```

Mathematical Statistics
Centre for Mathematical Sciences
Lund University with Lund Institute of Technology

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