When writing descriptions of general trends, orders of magnitude, change over time, etc, it is often useful to include simple trend graphs like this:
What tool can I use to create professional looking line graphs without having to provide underlying data?
I'm envisioning a web-app where I can add axes and data series, and drag the lines to appear how I want them. I don't want to draw the lines with a mouse -- they always end up looking choppy. I want something that looks like it was produced with a nice smooth data trend.
- Ideally web-based or platform-independent
- Produce a *.png (preferred) or *.pdf file (or at the very least a table of the resulting data, so I can reproduce the graph in excel)