====== Second Derivative of a Signal ======

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|{{:Second_Derivative.png}}\\ \\ **Second_Derivative**|                                        |
|**/Signal_Types=**                                                                                      |The type of signal to be processed      |
|**/Signal_Names=**                                                                                      |The names of the signals to be processed|
|**/Signal_Folder=**                                                                                     |The name of the signal folder           |

Compute the second derivative at each point of a signal. The first and last data points become DATA_NOT_FOUND(identified in the C3D file as a POINT Reliability value of &endash;1).

Derivatives are calculated using Finite Difference Algorithms.

Given the signal:

x(ti) for i=1, 2, ..., n
The second derivative is calculated using:
xDDot(ti)= (x(ti+1)-2x(ti)+x(ti-1))/( (ti+1)-(ti) )^2