Scan periodogram for a peak and return its properties
Method:
For f=log(fx)
fits a parabola 0.5(d2*x**2+d1*x)+f(2)
where d2=f(1)+f(3)-2f(2)
, d1=f(3)-f(1)
finds dxl
& dxp
such, that the linear and quadratic terms drop
by 0.7 in log, i.e. by a factor of 2 (dx=HWHI)
.
(C) Alex Schwarzenberg-Czerny, 1999-2005 alex@camk.edu.pl
Type | Intent | Optional | Attributes | Name | ||
---|---|---|---|---|---|---|
integer, | intent(in) | :: | n | periodogram length |
||
real(kind=SP), | intent(in) | :: | fx(n) | periodogram values |
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real(kind=TIME), | intent(out) | :: | xm | peak location (in index units, 1<xm<n) |
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real(kind=SP), | intent(out) | :: | fm | peak value; |
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real(kind=SP), | intent(out) | :: | dx | peak halfwidth HWHI,dx<0 no valid peak |