Derivative Issue

[mo103426]

Hello, 

I have a data set of a singular contraction creating a force-time curve. I am using the derivative function to identify the beginning and ends of the contraction, however, for some reason I am getting large spikes at the beginning and end of the measurement.

Can someone instruct me on how to get rid of the large spikes?

[GerdW]

Hi mo,

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@mo103426 wrote:

Can someone instruct me on how to get rid of the large spikes?

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1. Implement a correct calculation of the derivative.
2. Filter the spikes after your current derivative calculation…

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[dsb@NI]

Start with this for an implementation of the derivative:

Try your data. See which method produces expected results. Based on your knowledge of the experimental data, input appropriate initial and final conditions.

Depending on the method and your choice of initial and final conditions, you may see spikes at the beginning and end.

From the looks of your data, I am guessing that you expected the derivative to be zero at each end. To achieve that, make the initial condition equal to first data value and make final condition equal to last data value.