X.F.3.1 Simple extraction of components

A new post-processing class is created to allow the presentation of dynamic Results. Actually, this class only extracts the magnitude and phase for one finite element entity and one component, and saves it into an Array, for later output in a text file. The class is called “PostExtract” and has only one member data: “extracts” in which the extracted Results shall be stored.

The “initialize” method calls the constructor of the parent class and initializes “extracts” to a void Hash:

Then the sequence of operations to perform the extractions is described below. It is performed by the “calcOneGroup” method:

The method has nine arguments:

• The usual “db”, “lcName” and “scName” arguments.
• “refName”: is used to reference the extracted Results in “extracts” member data.
• “grpContent” the description of entities for which Results are extracted. This argument contains a String that must correspond to exactly one extracted value. For example: “Element 10”, “Node 17”.
• “resName”: a String containing the name of the Result stored in the DataBase “db” and from which one value shall be extracted.
• “extractMethod”: a String corresponding to the extraction method of “getResultCopy” DataBase method.
• “csId” the identifier of the coordinate system in which the Result shall be expressed. This argument can be an integer or a String.
• “component” The name of the component one shall extract. This is a String with 0, 1 or 2 characters. For example: "", "Y", "ZZ", "ZY"... (The void String is used if no extraction operation is necessary. This is the case when the Result obtained from the DataBase is already scalar.

Then the following sequence of operations:

• One builds a Group “grp” that shall be used for the extraction of a Result from the DataBase “db”:
          grp=Group.new  
          grp.Name=refName  
          grp.setEntities(grpContent)

• The Result is extracted:
          res=db.getResultCopy(lcName,scName,resName,extractMethod,grp,[])

• If the Result is vectorial or tensorial, the transformation of coordinate system is done:
          if (res.TensorOrder>0) then  
              res.modifyRefCoordSys(db,csId)  
          end

• One builds a new Result “compRes” by extraction of a component. Of course, if the Result is already scalar, one just performs an assignation operation:
          if (component.size==0) then  
              compRes=res  
          elsif (component.size==1) then  
              compRes=res.deriveVectorToOneScal("Component "+component)  
          elsif (component.size==2) then  
              compRes=res.deriveTensorToOneScal("Component "+component)  
          end

• Then, one retrieves an Array “grpHashRes” from “extracts” member data. If the Array is not found in the Hash by key “refName”, this means that this key appears for the first time. then, one initializes a new Array and inserts it in “extracts”.
          if @extracts.has_key?(refName) then  
              grpHashRes=@extracts[refName]  
          else  
              grpHashRes=[]  
              @extracts[refName]=grpHashRes  
          end

• Finally, one inserts extracted values in “grpHashRes”. The four values inserted are the output index, the frequency, the magnitude and the phase:
          compRes.set2MP  
          data=compRes.getData  
          mag=data[0][5]  
          phase=data[0][6]  
          grpHashRes << [compRes.getIntId(1),compRes.getRealId(0),mag,phase]

The class “PostExtract” also defines a method for the final processing of the values stored in “extracts” member data. This method, called “gnuplot” outputs the Results in text files created in “OUT_DYNAM” directory. Also, a “dat” file containing the gnuplot commands to create graphical outputs is created in the same directory. The name of this command file is the argument of “gnuplot” method: