smoothing a line between points plot.

I drew a line between points plot.

This graph is a kind of jagged line.

But, I want to smooth this graph like Excel "smoothed line"

I add an Excel example of this problem.

 

How can I solve this problem in Igor pro?

right: jagged line / left: smoothed line(which I want to draw)

Excel uses a spline function to achieve this result. You can do something similar in Igor by interpolating your data. Go to Analysis => Interpolate and choose Cubic Spline as Type (you can also try out Smoothing Spline and see if you like that better).

In reply to by chozo

OMG Thank you so much.

I tried two options of interpolation, cubic and smoothing.

In my case, the cubic spline seemed better than the Smoothing spline.

It seems that the choice of the best option may vary depending on plot by plot.

 

Yes, that is correct. If you want to get the same curve as Excel, use the code from Tony (of course you already had something like this ready ;).