Hello,
I've been having trouble fitting T1/T2 data to A(exp(-Bx)), which returns curve fit failure errors for some peaks (See representative errors below, either "fit did not converge" or "singular data", this occurs for about 1/3rd of my peaks). I saw some previous posts describing this error, but couldn't find anywhere that this was solved. There was a mention of noise levels being set to "0" for the various spectra, but I checked in Experiments->Spectra and they all have positive noise values. I tried setting error values for the x axis values (in the NMR Series window), but that didn't help either.
Any ideas/suggestions would be greatly appreciated!
With best regards,
Ian
Errors:
Problem with fitting: method = 3, nIter = 1000, noise = 26372.3139197, x = [1.0, 10.0, 50.0, 100.0, 200.0, 400.0, 700.0, 800.0, 900.0, 1000.0, 1500.0, 2000.0, 4000.0, 7000.0], y = [871943.625, 907566.875, 807618.5, 765851.125, 644529.875, 495262.125, 309121.5, 256548.6875, 219012.125, 174993.625, 90821.78125, 36496.984375, -6172.9375, 2147.7890625], 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, 0.0], yW = [26372.313919652483, 43875.722655780177, 20308.391243690468, 31612.202950474286, 20828.913357956037, 18001.255644778888, 13507.278567425126, 12153.040915308515, 9157.4527538545117, 10667.25802636409, 7796.3239340337659, 7493.1930825580766, 7008.2458626989319, 7025.5073455025777]: fit did not converge
Problem with fitting: method = 3, nIter = 1000, noise = 26372.3139197, x = [1.0, 10.0, 50.0, 100.0, 200.0, 400.0, 700.0, 800.0, 900.0, 1000.0, 1500.0, 2000.0, 4000.0, 7000.0], y = [680122.25, 718834.5, 670102.375, 642197.625, 522723.15625, 395582.25, 202050.25, 182093.625, 152838.5625, 150124.4375, 65464.53125, 34524.890625, 5077.265625, 23131.59375], 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, 0.0], yW = [26372.313919652483, 43875.722655780177, 20308.391243690468, 31612.202950474286, 20828.913357956037, 18001.255644778888, 13507.278567425126, 12153.040915308515, 9157.4527538545117, 10667.25802636409, 7796.3239340337659, 7493.1930825580766, 7008.2458626989319, 7025.5073455025777]: singular data
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