[Kst] Fixed step differentiation plugin

[Nicolas Brisset]

Hi,

I tried to use the fixed step differentiation plugin recently to visualize the quantification of my data. I was surprised by the result, so I checked the source and found out that it does not do simply (value[i]-value[i-1])/step but (value[i+1]-value[i-1])/2*step. Would anybody object to me changing the algorithm so that it's possible to see the difference between subsequent values using a step of 1.0?

The other point regarding this plugin is that we have it twice: as filter and as standard plugin. I think we should keep only one. And that reminds me of a discussion we had in the past. It's not really a filter plugin but it is nice to have it callable directly from the curve context menu. Should we maybe introduce a category "Quick plugin" to host non-filter plugins that should be callable like this?

Nicolas