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documentation/lagrit_manual/commands/derefine.txt

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+.. _derefine :
+
+> &nbsp_place_holder;
+
+>
+
+> **_DEREFINE_**
+
+> > This routine derefines a mesh by deleting points using the merge routine
+based on one of the following refine_types. **edge** will refine if element
+edge length is less then value. **volume** will merge if element volume is
+less than value. The merge routine will first attempt the smallest element
+edge then the next smallest, etc. **aspect** will derefine where aspect ratio
+is less than value. **pinchedge** will allow merging of adjacent points across
+a thin layer to eliminate the layer where it is too thin. **pinchedge** should
+be used only with pointtype1 and pointtype2 both equal to 2.
+
+Two criteria are currently enabled; **minsize** and **merge**. **minsize**
+allows merges if the calculation implied by refine_type is less than value.
+**merge** will merge the following first_point and second_point. The field
+option is not enabled and should be left default. The user specifies which
+merges are acceptable by designating the allowable pointtypes. Nodes with
+pointtype1 are merged to nodes of pointtype2. If pointtype1 and pointtype2 are
+both equal to 2, the code only merges if the nodes are both on the same
+material interface (use **pinchedge** if deleted nodes should be on different
+interfaces of the same material). **derefine** will not merge if an
+unacceptable element is created. **derefine** will work on material interfaces
+if all the children are set with the **settets** command. Various combinations
+of **derefine** may be used to improve the mesh. **recon** may be used to
+return to a delaunay mesh after using the **derefine** command.
+
+>
+
+> FORMAT:
+
+>
+
+>> **derefine/minsize**/field/pointtype1
+pointtype2/refine_type/first_point/last_point/stride/value
+
+**derefine**/**merge**/first_point/second_point
+>
+
+> EXAMPLE:
+
+>
+
+>> **derefine/minsize**//0 0/**aspect**/ 1 0 0/1.e-3
+
+**derefine/minsize**//0 2/**volume**/**pset,get**,apset/5.   
+**derefine/minsize**//10&nbsp_place_holder; 10**/edge**/1 0 0/5.   
+**derefine/minsize**//2 2/**pinchedge**/1 0 0/1   
+**derefine/merge**/21/22
+