I draw the splinechart, Y-axis is from -1 to 7. All my values more than 0, but because of auto-smoothing it somtimes displays lower 0. How i can avoid this?

I get this also

Hmm if there would be an extra point on X axis between the two on 0 then it would not go lower. I can't find a better solution.

It's not possible without adding more points, since a spline is a polynomal function which is built by interpolationg your given coordinates.

Have a look at this wikipedia article: http://en.wikipedia.org/wiki/Spline_(mathematics)

Alternatively, you can use a line chart which is 100% accurate: http://wiki.pchart.net/doc.chart.drawlinechart.html.

If you are plotting a known function, you can also use createFunctionSerie: http://wiki.pchart.net/doc.dataset.createfunctionserie.html

regards from Central Europe, Emi

It really would be handy to be able to cap the spline curve, especially when the curve hits an axis for example. The need to do this must be very common, stocks can't be priced less than $0, you can't have negative people showing up for a class, your sales team can't sell negative cars in March. I'm currently looking at my chart which shows negative hours worked for some days!

Even with lots of internal points with value=0 the spline still overshoots and it's just asking for comments from clients. Of course a line chart is more accurate, it's just not so ...sexy!

I've seen this capping feature on other charting programs, so let's add this to the wish list.

Just my two cents

Patrick