Large standard deviation values from linear fits?

[cwelch@…]

When I use the linear fits package in v. 7.03, I get very large standard deviation values. For example, when doing a Guinier plot to obtain Rg, I might get Rg = 44.142 +/- 5880 Angstroms. For this same example, the Chi-Squared value was 8.8941e-09. With previous versions of the NCNR Igor macros, I did not encounter such problems. Is this a known issue, or have I inadvertently set some parameter to the wrong value or done something else wrong? I do not encounter similar problems when using the Curve Fit features.

[srkline]

The /I=1 flag should be I=0, since the weights are calculated as 1/err -- since this procedure was written way back in time when that was the only acceptable way for the weights to be cast. fixed in r746