Error variable in IX_dataset sigvar is squared for variance

[cmarooney-stfc]

Herbert/herbert_core/utilities/classes/@IX_dataset/sigvar.m

Line 8 in c159375

wout = sigvar(w.signal_, (w.error_).^2);

Code is "out = sigvar(w.signal_, (w.error_).^2);"

On the assumption that error is always variance, it looks wrong that the error is squared.

[tgperring]

In the Herbert objects IX_data_1d, IX_data_2d etc., which inherit the abstract class IX_dataset, the property 'error ' is the standard error i.e. standard deviation, not the variance. [This is in contrast to sqw, d0d, d1d,... objects in Horace, where the corresponding property is the variance.] The argument that needs to be passed to the sigvar constructor is the variance. This is why in the code snippet you have quoted w.error_ is squared. So all is OK.

[cmarooney-stfc]

@tgperring This is good, thank you. As we regularly pass data w.s w.e where w.e is variance, it could be good to think of a way to highlight the exceptions to this rule. I did fix something in noisify where the error was squared on processing - hopefully that was a valid fix in the light of this comment.