Error bars drawn asymmetrically in errorbar()

Hello,

I am using the errorbar() function, and for some reason, the error bars are being drawn asymmetrically around the data points. In other words, the data point is not at the centre of the error bar. Can someone please explain why? Am I missing something?

The basic code:

x = w.^2 .* t ; y = lambdaFinal; yerr = deltaLambda;
errorbar(x, y, yerr, 'o', 'MarkerEdgeColor','red','MarkerFaceColor','red')

I have highlighted some of the egregious examples in the attached picture.

[madhan ravi]

Mind sharing the data?

Answer 1

[dpb]

Yeah, the y-axis scale is logarithmic so the positive and negative differences are scaled differently depending where on the log scale the point is. Those right around a decade change will be most noticeable as the change in scale is most pronounced.

The two particular points at the middle are such that the error magnitude is greater than or equal to the value so the lower error bar location is zero or negative. Can't plot nonpositive numbers on a log scale; errorbar silently just doesn't plot those whiskers. Probably should give a warning message; plot will, but errorbar doesn't.

hAx=gca;
hAx.YScale='linear';

and a revelation will occur! :)

[Anshuman Pal]

Perfect! Thanks a lot, the effect of logscale on error bars had never occurred to me.