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.TH cspect 1 "April 1993" "Scilab Group" "Scilab Function"
.so ../sci.an
.SH NAME
cspect - spectral estimation (periodogram method)
.SH CALLING SEQUENCE
.nf
[sm,cwp]=cspect(nlags,ntp,wtype,x,y,wpar)
.fi
.SH PARAMETERS
.TP 10
x
: data if vector, amount of input data if scalar
.TP
y
: data if vector, amount of input data if scalar
.TP
nlags
: number of correlation lags (positive integer)
.TP
ntp
: number of transform points (positive integer)
.TP
wtype
: string : \fV're','tr','hm','hn','kr','ch'\fR (window type)
.TP
wpar
: optional window parameters for \fVwtype='kr', wpar>0\fR
and for \fVwtype='ch', 0 < wpar(1) < .5, wpar(2) > 0\fR
.TP
sm
: power spectral estimate in the interval [0,1]
.TP
cwp
: calculated value of unspecified Chebyshev window parameter
.SH DESCRIPTION
Spectral estimation using the modified periodogram method.
Cross-spectral estimate of \fVx\fR and \fVy\fR is calculated when both
\fVx\fR and \fVy\fR are given. Auto-spectral estimate of \fVx\fR is calculated
if \fVy\fR is not given.
.SH EXAMPLE
.nf
rand('normal');rand('seed',0);
x=rand(1:1024-33+1);
//make low-pass filter with eqfir
nf=33;bedge=[0 .1;.125 .5];des=[1 0];wate=[1 1];
h=eqfir(nf,bedge,des,wate);
//filter white data to obtain colored data
h1=[h 0*ones(1:maxi(size(x))-1)];
x1=[x 0*ones(1:maxi(size(h))-1)];
hf=fft(h1,-1); xf=fft(x1,-1);yf=hf.*xf;y=real(fft(yf,1));
sm=cspect(100,200,'tr',y);
smsize=maxi(size(sm));fr=(1:smsize)/smsize;
plot(fr,log(sm))
.fi
.SH SEE ALSO
pspect
.SH AUTHOR
C. Bunks
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