ICurve.QueryTangent having problems with DistanceAlongCurve = 0.0

Discussion created by ajoos on Oct 27, 2011
Latest reply on Oct 28, 2011 by Neil
We have encountered a strange behaviour using ICurve.QueryTangent (on straight lines, not tested with other types). If you supply a value of exactly 0.0 (zero) for the DistanceAlongCurve argument, the resulting tangent is/has an empty geometry. Changing the value to something very close to 0.0 (zero), for example 5.0e-324, QueryTangent works as expected. The wrong behaviour doesn't seem to be dependant on the other values supplied to QueryTangent (extension method, length of the resulting tangent etc.)

This is our workaround which corrects the problem for us, however it's kind of an unpleasent hack. Can someone else confirm this behaviour? Could you coders at Esri look at this too, to see if the QueryTangent method can not handle zero values correctly (and if so, update the documentation accordingly or correct the problem)?

Thank you!