Comparing Models and Applications
It can be useful to compare two versions of the same model or application to get an overview of the differences between the two versions. To do so, click the Compare button () in the Compare section of the Developer toolbar. A Select Application window then opens, where you can select the Model MPH-file (the remote file) to which you want to compare the current model in the COMSOL Desktop (the local file). A comparison then starts, and the results, if there are any differences, appear as a tree in the Comparison Result window. The comparison tool compares all the settings in the entire model, including visible and invisible settings in the Model Builder and the Application Builder.
The Comparison Result Window
At the top of the Comparison Result window there is a toolbar with the following buttons:
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 New Comparison (), to make a new comparison. A New Comparison dialog box opens, where the default is that the Use open file check box is selected. Clear it to specify another Local file. Specify a Remote file and then click OK to perform a new comparison.
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 Update (), to update the comparison
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 Collapse All () and Expand All (), to collapse or expand all branches in the comparison tree
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 Load Comparison from File (), to load the results from another comparison from an XML-file.
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 Save Comparison to File (), to save the results from the current comparison to an XML-file.
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 Show Next Difference (), to move to the next difference in the tree with nodes that differ under Differences.
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 Show Previous Difference (), to move to the previous difference in the tree with nodes that differ under Differences.
Under Comparing files, you find the file paths to the local model and the remote model. The local model is typically the model open in the COMSOL Desktop, and it can have been modified after the last save. The left column is called Local file (Open application) when the local model is the opened model or application. When the local model is a new model that has not yet been saved, the left column is called Open application.
Under Differences, you can use the Filter results list to control filtering with the options No filter, Exclude all matching labels (the default), and Include all matching labels. The entries in the Regular expression field define what node labels to filter. You can make the filtering case sensitive by selecting the Case Sensitive button () box next to the list. The filter matching is done with regular expressions, and any label that contains a matching text will be either included or excluded. Filtering can be disabled by choosing No filter from the Filter results list. Click the Show Only Active button () next to the list to exclude inactive settings from the comparison. Such settings are not actively used in the current model state and do not typically appear in the COMSOL Desktop.
The tree of nodes with differences has a structure according the structure of the underlying model object, not the Model Builder or Application Builder trees. This means that the hierarchy can be somewhat different compared to the hierarchy seen in the Model Builder and Application Builder windows. The comparison includes all nonbinary differences in the model object that can be saved to disk, with some exceptions. For nodes that correspond to a node in the Model Builder or Application Builder trees, double-click the node (or right-click and choose Go to Source) in the tree of nodes with differences to display the corresponding node in one of those trees in the local file. When applicable, you can also right-click a node and choose Go to Remote Source to display the corresponding node in one of those trees in the remote file.
Below is a list of consequences of this design:
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The tree can show differences not visible in the Model Builder because they come from inactive settings hidden by another setting.
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Some settings and nodes in the Model Builder are not saved in the model object and will therefore not show in a comparison (Mesh Statistics, for example).
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No binary data are compared, so, for example, no differences in the solution will trigger a difference in the comparison.
Selecting a node in the tree will update the table under Comparing values below the tree. This table shows the attributes of the selected node, both in the local model (Local value column) and the remote model (Remote value column). This table is particularly interesting for the nodes labeled Attributes differ because they show the values that differ. Parent nodes can also show the same differences but typically with a larger number of attributes that have the same local and remote values. For differences that contain long entries or large arrays, there is an option to show a more detailed difference in a separate window for a selected table. Either double-click the table row or click the Detailed Comparison of Selected Attribute button () below the table to open the Compare Attribute window.