Re: [ferret_users] power spectrum 1d integrate to GMT

[Russ Fiedler <russell.fiedler@xxxxxxxx>]

Hi dessy,

Have you tried the external FFT functions that come with Ferret?

--------------

FFT_AMP(A)
    Computes fft amplitude spectra, normalized by 1/N, WITH CORRECTED
FREQ AXIS
    A: Variable with regular time axis. Specify time explicitly e.g.
fft_amp(var[l=1,96])
FFTA_SAMPLE(A)
    Computes fft amplitude spectra, normalized by 1/N
    A: Variable with regular time axis. Specify time explicitly e.g.
ffta_sample(var[l=1,120])
FFTA(A)
    Computes fft amplitude spectra, normalized by 1/N
    A: Variable with regular time axis. Specify time explicitly e.g.
ffta(var[l=1,120])
FFT_PHAS(A)
    Computes fft phase, WITH CORRECTED FREQ AXIS
    A: Variable with regular time axis. Specify time explicitly e.g.
fft_phas(v[l=1,96])
FFTP(A)
    Computes fft phase
--------------

Cheers,

Russ

On Tue, 2012-09-04 at 15:13 +1000, dessy berlianty wrote:
> Dear Ferret Users,
> 
> I need some suggestions to solve my problem.
> In order to make log-log scale of power spectrum 1d (based on time
> series), I have been tried gmt_power.jnl as suggestion by Steve Hankin
> in this link.
> After installation of GMT, I loss my way to continue the execution of
> gmt_power.jnl because of the following errors:
> 
> 
> yes? set data monthly_navy_winds
> yes? go gmt_power uwnd[x=180,y=0] uwnd x180y0 64
>  LISTing to file x180y0.tseries
> >>> Using GMT command: spectrum1d x180y0.tseries -Nx180y0 -S64
> -D30.4375
> sh: 1: spectrum1d: not found
>  **TMAP ERR: non-existent or not on line
>              x180y0.xpower
> SET DATA/EZ/var=freq x180y0.xpower
> Command file, command group, or REPEAT execution aborted
> yes? 
> 
> 
> 
> Thank you in advance for your time, and highly appreciate for any
> helps.
> 
> 
> 
> Best wishes,
> 
> 
> dessy
>