While digitizing points using the Engauge digitizer software, the points become automatically sorted by the value of the horizontal variable. This is fine for functions where there is only one "y" for every "x". But I have curves the have multiple y-values for every x.
Is there some setting that I should be using?
Change the curve type from Function to Relation. Use Settings / Curve Properties. Then choose 'Relation - Straight' or 'Relation - Smooth'. As you have seen, the default is 'Function - Smooth'.
Response taken from: https://github.com/markummitchell/engauge-digitizer/issues/241