.. _derefine : >  _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 _place_holder; 10**/edge**/1 0 0/5. **derefine/minsize**//2 2/**pinchedge**/1 0 0/1 **derefine/merge**/21/22