Plugin for binary data: channels with coefficient : y = a3*x^3 + a2*x^2 + a1*x +a0

Question

Hello,
I am bulding a plugin for extracting data from a binary file.
My problem is that the scaling of the values is not defiened by a linear equation (y = a1*x + a0 where conversion is easy with Factor and Offset properties of Channel), but by a cubic equation (y = a3*x^3 + a2*x^2 + a1*x +a0) with 4 coefficients. For the moment, I performed the operation in a loop over all the values of the channel... this takes a lot of time to convert all the values!!! Is there a more efficient way for multiplying array in VBA or channels in DIADem (for Plugins!!!)...?

Answer 1

Hi Ollac,
There is no way to efficiently apply polynomial scaling in a DataPlugin.  You could create each of the polynomial component terms with an eMultiplyProcessor type ProcessedChannel in the DataPlugin, but we can't add them together with another ProcessedChannel because you can't add a ProcessedChannel to another ProcessedChannel.  If the manual cell-by-cell scaling that you've already tried is too woefully slow, then I'd suggest exposing the raw data values to channels in the Data Portal and adding the "a0", "a1", "a2", "a3" polynomial coefficients as channel properties.  Once the raw data is in DIAdem, you can use the ChnCalculate() or the older and faster FormulaCalc() command to apply the polynomial scaling in-place based on the coefficients in the channel properties.  You might want the Data Plugin to add the "_Raw" suffix to the channel names and have the scaling VBScript remove the "_Raw" suffix or replace it with a "_Scaled" suffix so you don't accidentally apply the polynomial scaling twice.
Ask if you have questions about this,
Brad Turpin
DIAdem Product Support Engineer
National Instruments