Whoops, I managed to forget to reply to that.
I think it is getting confused because the noise level is set to 0. So I
tried setting it to 10000 (not sure if that is near correct but it doesn't
matter that much) and it worked ok. I'm not sure why the noise level is
coming out as 0, it should be using the spectrum noise. Check in the
dialog Experiment --> Spectra in the Spectra tab in the Noise Level
column.
Wayne
On Mon, 4 Apr 2011, David Yadin wrote:
>
> Dear all
>
>
>
> Sorry to post again, but I was wondering if anyone had answer to my query below.
>
>
>
> Many thanks
>
>
>
> David Yadin
>
>
>
> From: CcpNmr software mailing list [mailto:[log in to unmask]] On Behalf Of
> David Yadin
> Sent: 23 March 2011 18:11
> To: [log in to unmask]
> Subject: Track intensity changes
>
>
>
> Hi all
>
>
>
> I'm trying to use the 'track intensity changes' functionality to analyse my T1
> and T2 relaxation data. I've set up an NMR series (each point being one 2D
> experiment) and tried to fit an exponential to the data.
>
>
>
> I keep getting errors like the following:
>
>
>
> Problem with fitting: method = 3, nIter = 1000, noise = 0.0, x = [2.0, 4.0, 6.0,
>
> 8.0, 10.0, 16.0, 30.0, 40.0, 22.0, 60.0, 80.0, 100.0, 22.0], y = [40363184.5, 3
>
> 8421647.25, 34290384.25, 30890626.75, 29719230.25, 20810224.0, 10467649.25, 6704
>
> 151.75, 15830207.25, 2795667.390625, 708529.107421875, 281566.416015625, 1366670
>
> 6.625], xW = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
>
> yW = [512130.35068808583, 600012.37385196565, 374928.3352506322, 264703.85392259
>
> 23, 411991.04824293463, 449873.5353257347, 303816.35258713475, 139518.0396537332
>
> 6, 254633.46510434593, 99282.855433690347, 123689.41897544829, 108984.5978362939
>
> 8, 177204.66520992483]: fit did not converge
>
>
>
> I've plotted the peak heights and volumes using a different program and there is
> definitely exponential decay. I'm also a bit confused about why it says noise =
> 0.0.
>
>
>
> Have I done something wrong? Should I have my data as a pseudo-3D experiment
> rather than a series of 2Ds?
>
>
>
> Many thanks
>
>
>
> David Yadin
>
>
>
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