) study node provides a simplified interface for performing least-squares parameter estimation. Note that the Parameter Estimation study step can be used to fit multiple curves and it is compatible with all other study steps. This is opposed to The Curve Fitting Study, which only works for time dependent problems, and only allows fitting of a single curve. It has the following sections
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The Parameter Estimation study step is available with the following licenses
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) to open the fullscreen Select File window. Click the downward arrow for the Location menu (
) to choose Show in Auxiliary Data (
) to move to the row for this file in the Auxiliary Data window, Copy File Location (
), and (if you have copied a file location) Paste File Location (
).Click the Import button (
) to import the data from the source. Click the Refresh button (
) to update the data. You can also choose a Decimal separator. The separator can be either Point (the default) or Comma.
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Note that importing a file into a Local table is only supported for space-delimited *.txt or comma-delimited or semicolon-delimited *.csv files.
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Time (first default), the only setting for the time column is Time unit. Only one of the columns can be assigned as time column.
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Value (second default), this has settings for the Model expression, which is the value of the data according to the model in terms of global variables. For post-processing, the values in the file can be referenced using the Variable name. It is important to specify the Unit of the data, if this differs from the unit system of the model. Both the data and model expression are normalized with the Scale.
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Frequency, the only setting for the frequency column is the Frequency unit. Only one of the columns can be assigned as frequency column.
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Parameter, this has a list of parameters in the model as well as an option to specify the Unit. If the parameter is constant, it is better specify the value in the section below (Experimental Parameters).
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Ignored, does not do anything, so there are no settings, but it can reduce the need for manipulation of the data source.
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) button to add one of the parameters defined in the Settings window for Parameters under Global Definitions to the set of parameters to be estimated. Use the Move Up (
), Move Down (
), and Delete (
) buttons under the table to organize the data.
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) to browse to such a text file. You can also click the downward arrow beside the Load from File button and choose Load From (
) to open the fullscreen Select File window. The program appends the read names and values to the current table. The format of the text file must be such that the parameter names appear in the first column and the values for each parameter appear row-wise with a space separating the name and values, and a space separating the values. Click the Save to File button (
) to save the contents of the table to a text file (or to a Microsoft Excel Workbook spreadsheet if the license includes LiveLink™ for Excel®).
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The Least-squares time/parameter method list only appears in a model where there is a least-squares objective.
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Select All to store all the optimizations solutions in memory.
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Select Only last or Automatic (the default) to store only the last solution from the optimization job. If the there are Parametric Sweep study steps in an Optimization study, the default option (Automatic) will save the last solution from the optimization job and all solutions from the parametric jobs.
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Select Only last (the default) if you want to save only the last solution.
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Select Last N if you want to save the last N solutions. Then specify a positive integer in the Number of solutions to save field to define N (2 by default).
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Select Every Nth if you want to save every Nth solution. Specify a positive integer in the Save every Nth field to define N (10 by default to save every 10th solution).
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