| convolution [message #34613] |
Fri, 28 March 2003 09:08 |
Larry Morgan
Messages: 2
Registered: March 2003
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Junior Member |
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Hi,
I am at a loss to explain the output from the program below and although
it's not strictly an idl problem I was wondering if anyone could help me.
I want to convolve the two functions in the left half of the plot window
together. When I multiply their fourier transforms together and inverse
transform the result back I get what appears in the right hand window. This
is not at all what I expected although from everything I've read there is
nothing wrong with the method I have used.
Can anyone help me?
cheers
Larry
Pro convolve
xxx=((DINDGEN(20000))*0.01)
beamlong=(0.960944*exp(-((xxx-100.)^2)/(2*(10.6337^2))))+(0. 0390565*exp(-((xxx-100.)^2)/(2*(33.2939^2))))
loz_850=0.00060018403/(4.0*(((xxx-100.)/27.269890)^2.0)+1.0)
loz_850=loz_850/max(loz_850)
!p.multi=[0,2,1,0,0]
plot,xxx,loz_850,linestyle=1
oplot,xxx,beamlong
imconv_850=fft(fft(loz_850)*fft(beamlong),/inverse)
plot,xxx,imconv_850
!p.multi=0
end
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