Embedded Files
This tab allows studying the effect of different parameters on the calculated maximum burst rate.
It extends the script found in the "Burst Rate Analysis 1" page by encapsulating it in an external loop on a control parameter.
The layout of this tab is shown below:
(The figure above will be updated)
The principle of the search is as follows:
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The search for the maximum burst rate is controlled by the parameters in the green box shown above.
"Optimum Dtmin Search Algorithm" is either "Local Maximum" or "Savitzky-Golay Filter" (blue box in the figure above). In the first case, the algorithm stops the search as soon as the new burst rate is smaller than the previously calculated one. It is of course sensitive to noise in the calculated burst rate and is not recommended in general. The other algorithm stops when the new calculated burst rate reaches the threshold specified by the user (see parameter definition below). Using the series of burst rates computed during the search, the algorithm smooths the curve using a Savitzky-Golay filter and attempts to find a global maximum.
"Dtmin Offset" is the value added to either 0 (if "Use last Optimal Dtmin" is unchecked) or the last found optimal min burst separation (if "Use last Optimal Dtmin" is checked) at the beginning of each new search.
"Dtmin increment" defines the search granularity. The smaller this value, the larger the neumber of necessary steps will be and the slower the script.
"Threshold (%Max)" defines when the search is interrupted when the Savitzky-Golay algorithm is selected.
The control parameter to study is defined by the controls located in the red box shown above.
The type of parameter to study is selected from a pull-down menu:
In the example we will examine here, the parameter will be a "Constrained Burst Statistics", defined on the Burst Analysis page.
It could alternatively be a constraint by number ("Use N Largest/Smallest Statistics") or the "m" or "F" parameters of the Burst Search. Note that even though the "Min Burst Separation (ms)" is in this list, it is pointless to select it, since this parameter is actually incremented automatically in order to find the maximum burst rate.
The next parameters to define are the "Constraint Index" and the "Constraint Parameter Index".
The "Constraint Index" refers to the array of constraints defined in the Burst Analysis page. The first constraint has index 0 and so on. If there are more than one constraint in this array, enter the index of the constraint you want to study. If there is a single constraint defined in this array, the index to define is 0.
Constraints have 4 parameters: the statistics name (or alias), the type of range definition, and two values. The latter are the one that can be varied in this script. The "Constraint Parameter Index" specifies which of these two values will be incremented during the script. If this "Value 1", set this parameter to 0. Otherwise, set it to 1.
"Starting Parameter Value" defines the first value used in the study. Note that if you choose to use a logarithmic increment (see below), a strictly positive value needs to be chosen.
"Parameter Increment" is the value added (resp. multiplied) to the last parameter value in order to obtain the next parameter value, depending on whether a linear (resp. logarithmic) increment is chosen.
"# Steps" defines the number of iterations to perform.
"Logarithmic Increment" selects the type of parameter increment to use in the study
After each iteration, the result of the search is indicated in the 3 indicators:
"Max Burst Rate (Hz)
Var(Rate)/<Rate>
Current Optimal Dtmin (ms)
These values are also plotted in the "Burst Rate Analysis Graph 2".
If the search failed to define a maximum, the "Optimum Found" LED will not light up and the results will be "NaN" (Not a Number).
Note: if you want to have a look at the data used to find the maximum burst rate and the optimum min burst separation for each step, check the "Save Intermediate Results" box located above the graph legend (circled in red on the figure above). The pairs of (Dtmin, Burst Rate) calculated at each step will be saved in as many text files as there are steps in your study. Their names will use the root file name and an extension indicating which parameter value they correspond to.
As for all scripts, the script progression is indicated by a progress bar at the bottom of the page. The script can be interrupted by pressing the "Abort" button to the left of the progress bar.
The progress of the burst search for each individual step is indicated at the bottom of the window. Interrupting this step will also abort the script.
Information generated during the script is sent to the Notebook.
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