Hello, thank your for your answer. I tried both options:
* when I check the Use1DInterpolationForXYScatter to true, the range of values is increased too - for values in in the interval (0,1) is the range (-50,200) and it does not reflect reality (an interpolation polynom is too high?) - see pic. smooth_lines.png
* when I check the Use1DInterpolationForXYScatter to false the curve creates loops.
It seems I cannot use Smooth lines for this type of values.
What is your opinion?
Best Regards,
Daniela