GetMaxTotalConnectivity

Interface

MODULE FUNCTION obj_GetMaxTotalConnectivity(obj) RESULT(ans)
  CLASS(FEDOF_), INTENT(IN) :: obj
  INTEGER(I4B) :: ans
END FUNCTION obj_GetMaxTotalConnectivity

Description

The GetMaxTotalConnectivity method determines the maximum number of degrees of freedom (DOF) associated with any single element in the mesh. This value represents the largest connectivity array size needed to store all DOFs for any element, which is crucial for pre-allocating arrays in finite element assembly operations.

Parameters

• obj - Input, CLASS(FEDOF_), FEDOF object instance
• ans - Output, INTEGER(I4B), maximum connectivity size across all elements

Implementation Details

The implementation iterates through all elements in the mesh, calculates the total DOF for each element, and keeps track of the maximum value:

ans = 0
telems = obj%mesh%GetTotalElements()

DO ii = 1, telems
  tdof = obj%GetTotalDOF(globalElement=ii, isLocal=.TRUE.)
  ans = MAX(ans, tdof)
END DO

This efficient approach ensures that the returned value is large enough to accommodate the connectivity of any element in the mesh.

Usage Example

! Example to get the maximum connectivity size
INTEGER(I4B) :: maxConnSize
TYPE(FEDOF_) :: myDOF

! Get maximum connectivity size
maxConnSize = myDOF%GetMaxTotalConnectivity()

! Use this value to allocate arrays for element operations
INTEGER(I4B), ALLOCATABLE :: elemDOFs(:)
ALLOCATE (elemDOFs(maxConnSize))

! Now elemDOFs is guaranteed to be large enough for any element
! in the mesh, regardless of element type or polynomial order

Important Notes

1. This method is particularly valuable in heterogeneous meshes where different element types or polynomial orders are used
2. The returned value is often cached in the maxTotalConnectivity member variable to avoid recalculation
3. This method can be computationally expensive for large meshes as it loops through all elements

Related Methods

• GetTotalDOF - Used internally to calculate the DOF count for each element
• GetConnectivity - Returns the actual connectivity for a specific element
• GetConnectivity_ - Lower-level method for retrieving element connectivity

The GetMaxTotalConnectivity method is an important utility function for memory management in finite element codes, ensuring that sufficient memory is allocated for element-wise operations without excessive over-allocation.

Example 1

!> author: Vikas Sharma, Ph. D.
! date: 2025-06-08
! summary:  Testing GetMaxTotalConnectivity method of FEDOF class

PROGRAM main
USE BaseType, ONLY: TypeQuadratureOpt
USE FEDOF_Class
USE FEDomain_Class
USE AbstractMesh_Class
USE HDF5File_Class
USE Display_Method
USE GlobalData
USE Test_Method
USE ExceptionHandler_Class, ONLY: e, EXCEPTION_INFORMATION

IMPLICIT NONE

TYPE(FEDOF_) :: obj
TYPE(FEDomain_) :: dom
CLASS(AbstractMesh_), POINTER :: meshptr => NULL()
CHARACTER(*), PARAMETER :: &
  filename = "../../FEMesh/examples/meshdata/small_tri3_mesh.h5", &
  baseContinuity = "H1", &
  baseInterpolation = "Heirarchical", &
  testname = baseContinuity//" "//baseInterpolation// &
  " GetMaxTotalConnectivity test"

INTEGER(I4B) :: order = 1

TYPE(HDF5File_) :: meshfile
LOGICAL(LGT) :: isok

CALL e%setQuietMode(EXCEPTION_INFORMATION, .TRUE.)
CALL meshfile%Initiate(filename, mode="READ")
CALL meshfile%OPEN()
CALL dom%Initiate(meshfile, '')
meshptr => dom%GetMeshPointer()

CALL test1
CALL test2
CALL test3

CALL dom%DEALLOCATE()
CALL meshfile%DEALLOCATE()

CONTAINS

SUBROUTINE test1
  INTEGER(I4B) :: found, want

  order = 1

  CALL obj%Initiate(baseContinuity=baseContinuity, &
                    baseInterpolation=baseInterpolation, &
                    order=order, mesh=meshptr, &
                    ipType=TypeQuadratureOpt%equidistance)

  found = obj%GetMaxTotalConnectivity()
  want = 3
  isok = found .EQ. want

  CALL IS(found, want, testname//" test 1")
END SUBROUTINE test1

SUBROUTINE test2
  INTEGER(I4B) :: found, want

  order = 2
  CALL obj%Initiate(baseContinuity=baseContinuity, &
                    baseInterpolation=baseInterpolation, &
                    order=order, mesh=meshptr, &
                    ipType=TypeQuadratureOpt%equidistance)

  found = obj%GetMaxTotalConnectivity()
  want = 6
  isok = found .EQ. want

  CALL IS(found, want, testname//" test 2")
END SUBROUTINE test2

SUBROUTINE test3
  INTEGER(I4B) :: found, want

  order = 3
  CALL obj%Initiate(baseContinuity=baseContinuity, &
                    baseInterpolation=baseInterpolation, &
                    order=order, mesh=meshptr, &
                    ipType=TypeQuadratureOpt%equidistance)

  found = obj%GetMaxTotalConnectivity()
  want = 10
  isok = found .EQ. want

  CALL IS(found, want, testname//" test 3")
END SUBROUTINE test3

END PROGRAM main

Example 2

!> author: Vikas Sharma, Ph. D.
! date: 2025-06-08
! summary:  Testing GetMaxTotalConnectivity method of FEDOF class

PROGRAM main
USE BaseType, ONLY: TypeQuadratureOpt
USE FEDOF_Class
USE FEDomain_Class
USE AbstractMesh_Class
USE HDF5File_Class
USE Display_Method
USE GlobalData
USE Test_Method
USE ExceptionHandler_Class, ONLY: e, EXCEPTION_INFORMATION

IMPLICIT NONE

TYPE(FEDOF_) :: obj
TYPE(FEDomain_) :: dom
CLASS(AbstractMesh_), POINTER :: meshptr => NULL()
CHARACTER(*), PARAMETER :: &
  filename = "../../FEMesh/examples/meshdata/small_tri6_mesh.h5", &
  baseContinuity = "H1", &
  baseInterpolation = "Heirarchical", &
  testname = baseContinuity//" "//baseInterpolation// &
  " GetMaxTotalConnectivity test"

INTEGER(I4B) :: order = 1

TYPE(HDF5File_) :: meshfile
LOGICAL(LGT) :: isok

CALL e%setQuietMode(EXCEPTION_INFORMATION, .TRUE.)
CALL meshfile%Initiate(filename, mode="READ")
CALL meshfile%OPEN()
CALL dom%Initiate(meshfile, '')
meshptr => dom%GetMeshPointer()

CALL test1
CALL test2
CALL test3

CALL dom%DEALLOCATE()
CALL meshfile%DEALLOCATE()

CONTAINS

SUBROUTINE test1
  INTEGER(I4B) :: found, want

  order = 1

  CALL obj%Initiate(baseContinuity=baseContinuity, &
                    baseInterpolation=baseInterpolation, &
                    order=order, mesh=meshptr, &
                    ipType=TypeQuadratureOpt%equidistance)

  found = obj%GetMaxTotalConnectivity()
  want = 3
  isok = found .EQ. want

  CALL IS(found, want, testname//" test 1")
END SUBROUTINE test1

SUBROUTINE test2
  INTEGER(I4B) :: found, want

  order = 2
  CALL obj%Initiate(baseContinuity=baseContinuity, &
                    baseInterpolation=baseInterpolation, &
                    order=order, mesh=meshptr, &
                    ipType=TypeQuadratureOpt%equidistance)

  found = obj%GetMaxTotalConnectivity()
  want = 6
  isok = found .EQ. want

  CALL IS(found, want, testname//" test 2")
END SUBROUTINE test2

SUBROUTINE test3
  INTEGER(I4B) :: found, want

  order = 3
  CALL obj%Initiate(baseContinuity=baseContinuity, &
                    baseInterpolation=baseInterpolation, &
                    order=order, mesh=meshptr, &
                    ipType=TypeQuadratureOpt%equidistance)

  found = obj%GetMaxTotalConnectivity()
  want = 10
  isok = found .EQ. want

  CALL IS(found, want, testname//" test 3")
END SUBROUTINE test3

END PROGRAM main