; This batch file creates a plot of the power spectrum 
; of the simulated signal used in the example from Chapter 13,
; "Signal Processing", of _Using IDL_.

@sigprc01  ; compute time data sequence u

V = FFT(U) ; compute spectrum v

F = FINDGEN(N/2+1) / (N*delt) ; f = [0.0, 1.0/(N*delt), ... , 1.0/(2.0*delt)]

; log-log plot of power spectrum

PLOT, F, ABS(V(0:N/2))^2, YTITLE='Power Spectrum of u(k)', $
    /YLOG, XTITLE='Frequency in cycles / second', /XLOG, $
    XRANGE=[1.0,1.0/(2.0*delt)], XSTYLE=1